Perfomance Tool W2972 User manual

DIGITAL AUTOMOTIVE
MULTIMETER
OWNER'S MANUAL
Stock Number W2972/W2969
FOR YOUR SAFETY,
please read these instructions carefully and retain them for future use.
WARNING!
It is the owner and/or operators’ responsibility to study all WARNINGS, operating, and maintenance instructions contained
on the product label and instruction manual prior to operation of this product. The owner/operator shall retain product
instructions for future reference.
The owner and/or operator are responsible for maintenance, maintaining all decals or warning labels and while in use,
maintaining the unit in good working order. If the owner and/or operator are not fluent in English, the product warnings and
instructions shall be read and discussed with the operators’ native language by the purchaser/owner or his designee.
Make sure that the operator comprehends its contents. Safety information shall be emphasized and understood prior to
usage. The product shall be inspected per the operating instructions.
Users of this product must fully understand these instructions. Each person operating this product must also be of sound
mind and body and must not be under the influence of any substance that might impair their vision, dexterity or judgment.
Protect yourself and others by observing all safety information.
Failure to comply with instructions could result in personal injury and/or property damage!
If you encounter any problems or difficulties, please contact our customer service department at: 1-800-426-1262 between
6:30 a.m. and 4:30 p.m. Pacific time.
Due to continuing improvements, actual product
may differ slightly from photo shown.

SAFETY INFORMATION
WARNING!
To avoid possible electric shock or personal injury, and
to avoid possible damage to the Meter or to the
equipment under test, adhere to the following rules:
1. B efore using the Meter inspect the case. Do not
use the Meter if it is damaged or the case (or part of the
case) is removed. Look for cracks or missing plastic.
Pay attention to the insulation around the connectors.
2. Inspect the test leads for damaged insulation or
exposed metal. Check the test leads for continuity.
3. Do not apply more than the rated voltage, as
marked on the Meter, between the terminals or
between any terminal and grounding.
4. The rotary switch should be placed in the right
position and no any changeover of range shall be
made during measurement is conducted to prevent
damage of the Meter.
5. When the Meter working at an effective voltage
over 60V in DC or 30V rms in AC, special care should
be taken for there is danger of electric shock.
6. Use the proper terminals, function, and range for
your measurements.
7. Do not use or store the Meter in an environment of
high temperature, humidity, explosive, inflammable and
strong magnetic field. The performance of the Meter
may deteriorate after dampened.
8. When using the test leads, keep your fingers
behind the finger guards.
9. Replace the battery as soon as the battery
indicator appears. With a low battery, the Meter
might produce false readings that can lead to electric
shock and personal injury.
10. Remove the connection between the testing leads
and the circuit being tested, and turn the Meter power
off before opening the Meter case.
11. When servicing the Meter, use only the same
model number or identical electrical specifications
replacement parts.
12. The internal circuit of the Meter shall not be altered
at will to avoid damage of the Meter and any accident.
13. Soft cloth and mild detergent should be used to clean
the surface of the Meter when servicing. No abrasive and
solvent should be used to prevent the surface of the
Meter from corrosion, damage and accident.
14. The Meter is suitable for indoor use.
15. Turn the Meter power off when it is not in use and
take out the battery when not using for a long time.
Constantly check the battery as it may leak when it has
been using for some time, replace the battery as soon as
leaking appears. A leaking battery will damage the Meter.
INDEX
Cover Page pg. 1
Index pg. 2
Safety Information pg. 3
Electrical Symbols pg. 3
Specifications pg. 3
Meter Identification pg. 3
Basic Tests pg. 3
Setting Range Position pg. 3
AC/DC Voltage pg. 3
Measuring DC Amps/Milliamps pg. 4
Resistance Test pg. 4
Continuity Open Circuit Test pg. 4
Diode Test pg. 4
Mechanical Tests pg. 5
Engine RPM pg. 5
Measuring Dwell pg. 5
Battery/Starting/Charging pg. 5
No Load Battery Test pg. 5
Cranking Battery Load Test pg. 5
Battery Current Draw pg. 6
Finding Excessive Current Draw pg. 6
Charging System Voltage pg. 6
Engine Sensors Tests pg. 6
Throttle/EGR Valve Position, Air Flow pg. 6
Manifold Absolute Pres. MAP Sensor pg. 7
Barometric Pressure BARO Sensor pg. 7
Oxygen Position Sensor pg. 8
O2 Heater Circuit pg. 8
O2 Sensor Circuit pg. 8
Mass Air Flow MAF Sensor pg. 9
Temperature Sensor pg. 9
Hall Effect Sensor pg. 10
Fuse/Switch/Solenoid Tests pg. 10
Fuses/Switches pg. 10
Solenoid/Relays pg. 11
Ignition System Tests pg. 11
Distributor Cap/Rotor Resistance pg. 11
Variable Reluctance Sensor pg. 11
Crankshaft Timing Sensor pg. 11
Pick-up Coil Resistance pg. 12
Ignition Coil pg. 12
Coil Switching ON/OFF pg. 13
Ignition Wires pg. 13
Fuel System Tests pg. 13
C3 Meter Control Solenoid pg. 13
Measuring Fuel Injector Resistance pg. 14
Injector Test pg. 14
Injector Wiring Harness Test pg. 14
Maintenance & Troubleshooting pg. 15
Overrange Indication pg. 15
Zero Adjustment pg. 15
Automatic Polarity pg. 15
Alligator Clip Adapters pg. 15
Low Battery pg. 15
Battery Replacement pg. 15
Fuse Replacement pg. 15
Warranty pg. 16

DC (Direct Current) DC or AC
AC (Alternating Current) Low battery
Warning. Refer to the manual Earth ground
Dangerous voltage may be present Fuse
Diode Continuity test
AUTO Auto range Double insulated
Display : LCD, 1999 Counts updates 2/sec
LCD size : 46 x 24mm
Polarity Indication : “-” Displayed automatically
Over-range Indication : “1” Displayed far left
Low Battery Indication : “ ” Displayed
Range select : Auto or Manual
Operation Temperature : 0°C to 40°C, less than 80%RH
Storage Temperature : -10°C to 50°C, less than 85%RH
Battery Type : 1.5V x 2, AAA size
Dimension (H×W×D) : 150×70×22mm
Weight : Approx. 150g
1. LCD Display Large LCD for easy reading
2. Hold Button Retains date on the display
3. Diode/Continuity Check diodes/circuits audible
4. Ohms Measure resistance
5. DC Volts Measure DC voltage from 0 to 1000V
6. Range Selector Set meter functions
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ELECTRICAL SYMBOLS
SPECIFICATIONS
+ -
1
2
3
4
5
6
7
8
9
10
11
12
7. RPM Tachometer Measure Engine RPM
8. Power Button Push for power on and off
9. Dwell Measure dwell angle on ignitions/solenoids
10. DC Amps Measure direct current from 0 to 10 amps
11. AC Volts Measure AC voltage from 0 to 750V
12. Test Lead Jacks Test lead locations
METER IDENTIFICATION
BASIC TESTS
Setting Range Position
Select the largest value the multimeter can measure
within the test settings.
Example: If you’re testing 100V DC turn the Range
Selector knob to 200V DC, then the highest voltage
the meter can measure is 200V in that range.
Voltage Function AC – DC
Determine the current you’re testing AC or DC.
Select the largest value within the range you’re testing.
1. Insert the BLACK or ground probe to the
COM on the meter.
2. Insert the RED or positive probe to
the on the meter.
3. Touch RED probe to the circuit coming from
the power supply.
4. Touch BLACK probe to ground or the
negative (-) circuit.
5. Read the meter display for your results.
Note: If you don’t know positive (+) and which
side is negative (-), then arbitrarily connect the
RED test lead to one side and the BLACK to the
other. The multimeter automatically senses
polarity and will display a minus (-) sign when
negative polarity is measured.
WARNING: When measuring voltage be sure the
red test lead is in the terminal marked V. If the test lead
is in and Amp (A) or Milliamp (mA) terminal you may
be injured or the meter damaged.
DC Current Function
This meter measures DC current from 0 to 10A. If the
current exceeds 10A, the internal fuse will blow and
will need to be replaced. The capability of isolating
current drains and short circuits are some applications
for DC Current.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into “10A” test lead jack or
“mA” test lead jack.
3. Disconnect the circuit from power where you want to
measure current. Possible ways to do this are by
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BASIC TESTS CONT.
removing wires from a threaded power terminal.
Separate the wiring harness at the plug, or worst case
scenario, cut the wires.
4. Disconnect wiring harness.
5. Attach your alligator clips to the probes, black on
black, red on red.
6. Connect RED alligator clip to one side of the
disconnected circuit.
7. Connect BLACK alligator clip to remaining side of
disconnected circuit.
8. Turn multimeters range selector to 10A DC
position, or 200mA position.
9. Read the meter display for your results. If the results
displayed are negative (-), then reverse RED and
BLACK test leads. See display for corrected results.
Resistance Test
This meter measures resistance from 0.1Ω to
20MΩ. Infinite resistance is shown with the “1”
figure on the left side of display. This meter can
measure resistance on anything called out in your
vehicles service manual. Testing light bulbs, ignition
coils/wires, engine sensors, and wires circuits, are
just some of the tests the Ohms function can do.
1. Turn circuit power off to get a resistance
measurement and avoid possible damage to the
meter or electrical circuit getting tested, turn off all
electrical power to the circuit.
2. Insert BLACK test lead into COM test lead jack.
3. Insert RED test lead into test lead jack.
4. Turn multimeters range selector to 200Ω range.
5. Touch RED and BLACK multimeter leads
together and view reading on display. Display
should read typically 0.2Ω to 1.5Ω. If display
reading was greater than 1.5Ω, check both ends of
test leads for bad connections. If bad connections
are found, replace test leads.
6. Connect RED and BLACK test leads across
component where you want to measure resistance.
When measuring resistance, polarity is not
important. The test leads just have to be connected
across the component.
7. Turn multimeters range selector to desired OHM
range. If the approximate resistance is unknown, start
at the largest OHM range and decrease to the
appropriate range as required. View reading on
display. Note range setting for correct units.
NOTE: 2KΩ = 2,000Ω; 2MΩ = 2,000,000Ω
For precise resistance measurements, subtract the
test lead resistance found from the display reading.
Do this for resistance measurements less than 10Ω.
Continuity Test
A quick way to check if you have an open or closed
circuit. The meter beeps when the circuit is closed
or shorted, so you don’t need the meters display in
view. A common automotive use is checking for
blown fuses, proper switch operation, and broken or
shorted wires.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn meters range selector to function.
4. Touch RED and BLACK test leads together to
test continuity. You should hear a tone to verify.
5. Connect RED and BLACK test leads across the
circuit where you want to check for continuity. If you
hear tone the circuit is closed or shorted. If there is
no tone the circuit is open.
Diode Test
Automotive alternators generates AC voltage, the
diode inside converts it to DC voltage allowing
current to flow in only one direction. When positive
voltage > 0.5V, is applied to the anode side of the
diode, the diode will turn on and allow current to flow.
If this same voltage is applied to the cathode side,
the diode would remain off and no current would flow.
When testing the diode both sides need to be
checked, anode-to-cathode, and cathode-to anode.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn the meters range selector to function.
4. Touch RED and BLACK test leads together to
test continuity. The display should show 0.00 and an
audible tone should be heard.
5. Disconnect one end of the diode from the circuit.
The diode must be totally isolated from circuit in
order to verify its function.
6. Add the alligator clips and connect RED clip to
one side of the diode.
7. Connect BLACK clip to the other end of the diode.
View results on the display, you should see one of
three things. A typical voltage drop of 0.7V, no
voltage drop at all, or the meter will display “1” on
the far left (overranging). Record the results.
8. Now switch the RED and BLACK clips and view
the results. If the display showed no voltage drop in
either directions, then the diode is shorted and needs
to be replaced. If the “1” appears in both directions,
then the diode is an open circuit and needs to be
replaced. If the display reads > 0.5V in one direction
and the “1” appears in the other direction then the
diode is good and functioning properly.
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No Load Battery Test
Before testing the starting/charging system, first test
the battery to make sure it is fully charged.
1. Turn Ignition OFF.
2. Turn ON headlights for approx. 10 seconds to
dissipate surface charge.
3. Insert BLACK test lead into COM test lead jack.
4. Insert RED test lead into test lead jack.
5. Disconnect positive (+) red battery cable. Be sure
positive cable clamp is securely away from the battery.
6. Add the alligator clips and connect RED clip to
the positive (+) terminal of battery.
7. Connect BLACK clip to the negative (-) terminal
of battery.
8. Turn multimeter range selector to 20V DC range.
View voltage results on the display.
Voltage Displayed Percentage of Charge
12.75V or greater 100%
12.45V 75%
12.35V 50% Charge before any
further tests.
12.15V or less 25% Charge before any
further tests.
Cranking Battery Load Test
This test puts a load on the battery to determine if
there’s enough voltage delivered to the starter under
cranking conditions.
1. Disable ignition system so vehicle won’t start. Refer
to vehicle service manual for disabling procedure.
2. Insert BLACK test lead into COM test lead jack.
3. Insert RED test lead into test lead jack.
4. Add the alligator clips and connect RED clip to
positive (+) terminal/post of the battery.
5. Connect BLACK clip to negative (-) terminal/post
of the battery.
6. Turn meter range selector to 20V DC.
7. Crank engine for 15 seconds continuously while
observing display. An assistant may be needed so
you’re able to watch the display. Battery voltage should
be at least 9.6 volts at the end of the 15 second load
test with battery temperature at 70 degrees.
Battery Voltage Temperature
After load Test of Battery
9.6V 70 Deg. F and above
9.5V 60 Deg.
9.4V 50 Deg.
9.3V 40 Deg.
9.1V 30 Deg.
8.9V 20 Deg.
8.7V 10 Deg.
8.5V 0 Deg.
5
MECHANICAL TESTS
Engine RPM
When checking engine RPM the meter results must
be multiply by 10 to get the final figure. For
example, if your meter display reads 65 and is set
to 6 cylinder RPM, the actual engine RPM is 10
times 65 or 650 RPM.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Connect RED test lead to the TACH signal wire
from the DIS Ignition Module if the vehicle is equipped
with a Distributor less Ignition System. The TACH
signal wire going from the DIS module to the vehicle
engine computer. Refer to vehicle service manual for
the wiring diagram. Vehicles with distributors, connect
RED test lead to negative side of primary ignition coil.
4. Connect BLACK test lead to a good vehicle ground.
5. Turn the meters range selector to the correct
cylinder setting, 8CYL, 6CYL, or 4CYL.
Engine RPM is measurement while engine is running.
5. Take the display results and multiply by 10 to get
actual engine RPM.
Measuring Dwell
Dwell angle can be measured and set on breaker point
ignition systems. Dwell is the length of time, in
degrees, the breaker points remained closed. The
correct dwell angle is extremely important for proper
engine performance. Another application for dwell is in
testing the mixture control solenoid on GM feedback
carburetors. For dwell angle of your breaker point
ignition system connect as follows.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Connect RED test probe to the negative terminal
side of the primary ignition coil. Refer to your vehicles
service manual.
For measuring dwell angle on GM mixture control
solenoids the meter connections stay the same.
1. Connect RED probe lead to ground side or
computer driven side of solenoid. Refer to vehicle
service manual for solenoid location.
2. Connect BLACK test lead to a good vehicle ground.
3. Turn the meters range selector to DWELL and
the correct cylinder setting, 8CYL, 6CYL, or 4CYL.
View reading on display.
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BATTERY/STARTING/CHARGING
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7. With accessories in the off position, no radio, or
lights etc. View and record the results from the display.
8. Open throttle, keep engine speed between 1500
and 2500 RPM. Have an assistance help hold
speed so you can view and record the results from
the display.
9. Fully load the electrical system by turning on the
lights, windshield wipers, and the blower fan on high.
10. Turn off all accessories, return engine to idle
and shut off. Refer to vehicle service manual for
recommended voltage outputs. If voltage readings
were as expected, then charging system is normal.
Typical charging system output voltages:
At normal idle, display should read 13.2 to 15.2 volts.
With idle speed increased, voltage reading should
not change by more than 0.5 volt.
With idle speed increased under load, voltage
should not drop under 13 volts.
If any of the above results were less than the
vehicles specifications check the following.
Check for corroded battery terminals, a loose belt,
bad voltage regulator, alternator, or poor terminal
connections.
Throttle Position/EGR Valve Sensors
Throttle Position/EGR Position Sensors are
potentiometers or a variable resistor. The ECU uses
the information provided by the sensors to
determine the position and direction of movement.
The following are applications for a position sensor;
Throttle, EGR valve, and Vane air flow.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Disconnect wiring harness from sensor. Refer to
vehicle service manual for your vehicles pin
identifications. You’ll be looking for the power,
ground, and signal pin locations. Typically you’ll find
the signal pin in the center of the three pins. If you
have four pins your sensor incorporates an idle
Battery Current Draw
Test to determine the amount of current being drawn
from the battery with the ignition key off. This test
helps to identify possible sources of a short or
excessive battery current draw. Excessive draw
could lead to shortened battery life, or a dead battery.
1. Ignition OFF including all accessories. Be sure
trunk, hood, and dome lights are all OFF.
2. Insert BLACK test lead into COM test lead jack.
3. Insert RED test lead into the “A” (or mA) test
lead jack.
4. Disconnect positive (+) red battery cable.
5. Add the alligator clips and connect RED clip to
positive (+) battery terminal/post of the battery.
6. Connect BLACK test lead to positive (+) red
battery cable (that as disconnected).
DO NOT start vehicle during this test, doing so will
damage the meter, and void warranty.
7. Turn meters range selector to 10A DC (or 200
mA) position.
8. View results on display, typical current draw is 0.1
ampere (100mA). Refer to vehicle service manual
for your vehicles specific Engine off Battery Current
Draw. Vehicle clocks, ECU’s and presets are
calculated in the normal 100mA draw.
Finding Excessive Current Draw
Display reading in the steps above are well outside
manufacturer’s specifications.
1.While watching the meter display remove fuses
from the fuse box one at a time until source of
excessive current draw is located. When the
suspect fuse is pulled there should be a drop in the
amps displayed on the meter. For non-fused circuits
such as headlights, relays, and solenoids it may
involve unplugging the unit from the wiring harness.
When the source of excessive current drain is found
service as needed.
Charging System Voltage
Check the charging system for output voltage.
Charging system provides power to maintain the
battery and feed power to the rest of the vehicles
electrical systems (lights, fan, radio etc).
1. Insert BLACK test lead into COM
2. Insert RED test lead into test lead jack.
3. Add the alligator clips and connect RED clip to
positive (+) terminal/post of battery.
4. Connect BLACK clip to negative (-) terminal
of battery.
5. Turn meters range selector to 20V DC range.
6. Be sure the meter and connecting wire are clear
from all moving parts. Start engine and let it idle.
BATTERY/STARTING/CHARGING CONT.
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ENGINE SENSORS TESTS
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+5V in
Signal Out
Ground
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switch, still typically both signal and idle pins are in
the center.
4. Add the alligator clips and connect the RED
clip to the sensors POWER pin.
5. Connect the BLACK clip to the sensors
GROUND pin.
6. Turn meters range selector to 20K Ω range.
7. View and record the reading displayed.
The results should show a small amount of
resistance. If the meter shows over range the
circuit is open and the sensor is defective.
8. Move the RED alligator clip to the sensors
SIGNAL pin.
9. Find the linkage on the Throttle Position Sensor,
manually move the throttle linkage cycling from
closed to fully open.
10. Watch the meter display, the reading will either
increase or decrease resistance.
Some throttle position sensors include a WOT, Wide
Open Throttle switch. These switches are tested like
the other switches in the Fuse/Switch section.
11. Find the vane on the Vane Air Flow Sensor,
typically on or near the multiport electronic fuel injector.
12. Slowly open the butterfly valve from closed to
open by pushing on it. This is the normal function of
the valve and will not harm the sensor.
13. Watch the meter display, the reading will either
increase or decrease resistance.
Some vane air flow sensors have an idle switch and
an intake air temperature sensor in addition to a
potentiometer. If so equipped these switches are
tested like the other switches in the Fuse/Switch
section.Refer to vehicle service manual for
recommended resistance outputs.
EGR Valve Position Sensor
1. Find the vacuum port on the EGR Valve
Position Sensor.
2. Remove the vacuum hose from EGR valve.
3. Connect a hand vacuum pump (W87030) to the
EGR valve.
4. Add the alligator clips and connect the RED
clip to the sensors signal pin (typically the center).
5. Connect the BLACK clip to a good body GROUND.
6. Slowly apply vacuum to the EGR valve. Typically,
6 - 10 inches of Hg. should fully open the valve.
7. Watch the meter display, the reading will either
increase or decrease resistance. Refer to vehicle
service manual for recommended resistance outputs.
• A good sensor should show an increase or
decrease in the resistance as the sensor is opened
and closed.
• A bad sensor will have no change in resistance.
ENGINE SENSORS TESTS CONT.
MAF vs MAP
Manifold Absolute Pressure (MAP) is a sensor to
measure vacuum, the computer calculates the
engine air flow based on the vacuum, throttle
position, and intake air temperature.
Mass Air Flow (MAF) is a sensor that measures the
actual air flow going into the engine
MAP/BARO Sensors
These sensors send signals to the ECU indicating
atmospheric pressure and/or engine vacuum. There
are two different types of MAP sensors. The first,
depending on the vehicle manufacturer may be a
frequency generator used by Ford. The other type
MAP may send a DC voltage signal to the ECU.
This is the most common used by Honda, Toyota,
Honda, GM etc. Refer to your vehicle service
manual for the type MAP sensor your vehicle uses.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. For this test you’ll need to back probe or add
jumper leads from the A and C pin in the harness. If
adding jump leads disconnect the MAP from the
wiring harness and the vacuum line from the sensor.
Special back probe lead attachments are available
from most electronic stores (not included).
4. Connect a hand held vacuum pump to vacuum
port on MAP sensor, our model W87030.
5. Identify the A, B, and C pin/wire location on the
MAP harness connection. Connect a jumper wire
between Pin A on wiring harness and sensor.
6. Connect another jumper wire between Pin C
on wiring harness and sensor.
7. Add the alligator clips and connect RED clip to
lead to sensor Pin B.
8. Connect the BLACK clip to a good vehicle
body ground. Jumper leads/back probes should be
isolated so they can’t touch each other.
9. Turn the Ignition to the ON position but do not
start the engine.
10. Turn the meters range selector to 20V DC range
for DC signals, and 4CYL for Frequency signals.
11. With vacuum at 0 in. Hg. your DC volts should
be approximately 3V or 5V. With a Frequency MAP,
when testing a Ford, your display reading should be
between 4532 to 5021 RPM’s, (Display RPM x 10)
For other frequency type MAP sensors refer to your
vehicle service manual for MAP sensor specifications.
12. With the Vacuum pump attached to the MAP
slowly apply vacuum. Do not exceed 20 in. Hg or
you’ll damage the MAP sensor. Voltage and RPM
readings should decrease as vacuum increases.
Refer to your vehicle service manual for voltage and
frequency drops to increasing engine vacuum.
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Use the following equation to convert your recorded
RPM to Frequency Hz = RPM ÷ 30.
Typical Vacuum to Frequency Results (Ford)
Hg (Vacuum) Hz (Hertz)
0 159
3 150
6 141
9 133
12 125
15 117
18 109
• A good sensor should show an increase or
decrease in the output voltage as the sensor is
opened and closed. A bad sensor will have no
change in resistance
• A good sensors output voltage or frequency (RPM)
fall within manufacturers specifications at 0 Hg. or
decrease with increasing vacuum.
• A bad sensors output voltage or frequency (RPM)
won’t fall within manufacturers specifications at 0
Hg. or show change with increased vacuum.
Oxygen Sensor O2
The Oxygen Sensor is used to measure the exhaust
gas concentration in the exhaust system. The ECU
uses the information to calculate and, if required,
adjust the air fuel ratio so that catalytic converters
can function efficiently. The sensor sends
information to the ECU based on the amount of
oxygen in the exhaust system and adjusts the air/
fuel ratio as needed. The two most common types
of O2 Sensors used are Zirconia and Titania. In
addition, when testing these two types you’ll need to
know if they are heated or unheated. If the sensor
has 3 or more wires, then your vehicle uses a
heated O2 sensor.
• A low voltage, high resistance, indicates a lean
exhaust, or too much oxygen.
• A high voltage, low resistance, indicates a rich
exhaust, or not enough oxygen.
Refer to illustration for appearance differences of
the two sensor types.
ENGINE SENSORS TESTS CONT.
Any time dealing with the exhaust system let the
vehicle cool down before proceeding. Although
these sensors can be checked in the vehicle, the
following test is done with the sensor removed.
NOTE: Never apply external voltage to the zirconia
sensors for testing, this may damage it.
1. Remove the Oxygen Sensor from the vehicle,
use the special slotted socket to avoid damaging
the wires.
2. Insert BLACK test lead into COM test lead jack.
3. Insert RED test lead into test lead jack.
O2 Heater Circuit
The following is for testing the heater circuit of the
O2 Sensor. Refer to your vehicles service manual for
the location of the heater pins in the wiring connector.
1. Add the alligator clips and connect the RED
clip to either of the two pins.
2. Connect the BLACK clip to remaining heater pin.
3. Turn the meters range selector to the 200Ω range.
4. View and record the display readings. Compare
them to the manufacturer’s specification in your
vehicles service manual. When completed remove
the test leads from the sensor.
O2 Sensor Circuit
The following is for testing the Oxygen Sensor
Circuit. Refer to your vehicles service manual for
the location of the ground pin and the signal pin in
the wiring connector. Also, know the type of O2
Sensor your vehicle uses, Zirconia type or Titania
type. A propane torch is needed to conduct this test.
1. Connect the BLACK alligator clip to the sensors
ground pin.
There are two different ways the sensor could be
grounded. The outside housing of the sensor, or the
ground will be in the wire harness connection. 1 and
3 wire sensors use the housing, while 2 and 4 wire
sensors have the ground in the harness connection.
2. Connect RED alligator clip to sensors SIGNAL pin.
3. Turn the meters range selector to 2V for
Zirconia or 200Ω for Titania.
4. Lock the pliers on the hex socket drive of the sensor.
5. Secure and light the propane torch and set it to a
mild flame. Heat the sensors tip as hot as possible
with the mild flame. Do not heat the tip to the point
of glowing.
The oxygen sensor must be hot, about 600 degrees
or higher, before it will start to generate a voltage
signal. Hold the sensor as close as possible to the
torch flame to quench the sensor tip. This will deplete
the sensor of oxygen signaling a Fuel Rich Condition.
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Heated Type
3-4 Wires
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Unheated Type
1-2 Wires

Zirconia Sensor: Meter display reading should be >0.6V
Titania Sensor: Meter display should show variable
resistance as flame temperature changes.
6. Now move the torch flame away fron the sensor
tip. This will allow oxygen to be drawn into the flame
and signal a Fuel Lean Condition.
Zirconia Sensor: Meter display reading should be <0.4V
Titania Sensor: Meter display should show an over
range with resistance set at the highest range.
7. Let the sensor cool then repeat the above test to
verify the results.
8. Turn the propane torch off, let the sensor cool
and remove the alligator test clips.
• A good heater circuit’s output resistance is within
manufacturer’s specifications.
• A good sensor circuit signal changes when moving
from a rich to a lean exhaust condition.
• A bad heater circuit output resistance is not within
manufacturer’s specifications.
• A bad sensors signal does not change when
moving from a rich to lean exhaust condition.
• A bad sensors signal moves between lean to rich
condition to slowly, >3 seconds.
Typically drivers don’t react until the MIL (Check
Engine) light come on
The following are symptoms of a failing Oxygen
Sensor prior to the MIL getting triggered.
• Increased tailpipe emissions
• Increased fuel consumption
• Hesitation on acceleration
• Stalling or a rough idle
MAF Sensors
This sensor send a signal to the ECU indicating the
air volume entering the engine. There are three
types of MAF sensors, the signal sent may be a DC
voltage, high frequency, or a low frequency.
This meter can only test DC voltage and low
frequency MAF sensors. High frequency MAF
sensors were common on some 1989 and newer
GM vehicles. Refer to your vehicle service manual
for the type MAF sensor your vehicle uses.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Add the alligator clips and connect the RED
clip to the sensors signal pin (typically the center).
4. Connect the BLACK clip to a good body GROUND.
5. Refer to your service manual for the MAF
location, identify the power, ground, and signal pin
ENGINE SENSORS TESTS CONT.
locations. Typically you’ll find the signal pin in the
center of the three pins.
For this test you’ll need to back probe or pierce the
signal wire in the MAF wire connection.
Refer to vehicle service manual for best way to
connect to MAF signal wire.
6. Turn Ignition KOEO (Key on engine off, do not
start engine).
7. Turn the meters range selector to 20V DC range
for DC signals, and 4CYL for Frequency signals.
Your DC volts should be approximately 1V or less.
With a Frequency MAF your display reading should
be between 314 to 347 RPM’s, for the GM low
frequency type sensor, (display RPM x 10).
Refer to your service manual for your specific
vehicles MAF sensor specifications.
Use the following equation to convert your recorded
RPM to Frequency Hz = RPM ÷ 30.
8. Turn the Ignition to the ON position and start the
vehicle. Be sure all wires, and leads are clear of
moving parts. At idle the voltage and RPM reading
should increase from your earlier results. As you rev
the engine both values should continue to increase.
Refer to vehicle service manual for charts relating
MAF sensor voltage or frequency (RPM) to
increasing air flow.
Use the following equation to convert your recorded
RPM to Frequency Hz = RPM ÷ 30.
• A good sensors output voltage or frequency (RPM)
fall within manufacturer’s specifications with KOEO,
or increase with increased air flow.
• A bad sensors output voltage or frequency (RPM)
won’t fall within manufacturer’s specifications, or
show change with increased air flow.
Temperature Sensor
A typical Temperature Sensor or thermistor are
thermally sensitive resistors whose prime function is
to exhibit a large, predictable and precise change in
electrical resistance when subjected to a
corresponding change in body temperature. The
hotter the sensor gets, the lower the resistance
becomes.
Typical Thermistor applications:
• Engine Coolant Temp. (ECT)
• Vane Air Temp, (VAT)
• Air Change Temp. (ACT)
• Throttle Body Temp (TBB)
• Manifold Air Temp. (MAT)
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Perform the following test on an engine that has not
been run or has cooled.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Disconnect the wiring harness from the
temperature sensor. Refer to your vehicle service
manual for the location of the specific temperature
sensor you wish to test.
The Intake Air Temperature Sensor needs to be
removed for testing, all other temperature sensors
can remain on the vehicle for testing.
4. Add the alligator clips and connect the RED clip
to either pin on the Intake Air Temperature Sensor.
5. Connect the BLACK clip to the remaining pin.
6. Turn meters range selector to largest Ω range,
decrease to the next lower range until the appropriate
range is found. View and record the results.
7. Heat up the sensor, the best method is to use a
hair dryer or heat gun. Do not use open flame to
conduct this test as some sensors are made of
plastic. Hot water can be used if the sensor has a
sealed temperature probe. If wires are exposed
liquids should be avoided. Heat up sensor, view and
record the smallest reading displayed as the sensor
is heated.
8. When the test is completed, disconnect the meter
and reconnect the sensor to the wiring harness.
For the following test the engine should be warmed
up. Let the engine idle until it’s close to operating
temperature. Feel the upper radiator hose, it should
be warm, not necessarily hot, (be cautious).
1. Turn the engine off with the ignition key in the
off position.
2. Disconnect the wiring harness from the sensor,
leave the sensor mounted in the car.
3. Reconnect the meter test clips and view and
record the readings from the display.
A good temperature sensors resistance, with the
engine hot, should be a minimum of 350 Ω less than
the reading when the engine was cold or resistance
should fall within manufacturer’s specifications.
A bad temperature sensors resistance will be
unchanged meaning an open or a short circuit.
Hall Effect Sensor
A Hall Effect sensor is a transducer that varies its
output voltage in response to a magnetic field. Hall
Effect sensors are used for proximity switching,
positioning, speed detection, and current sensing
applications. These sensors are used whenever the
vehicle ECU needs to know speed and position of a
rotating object. Examples of use are ignition
ENGINE SENSORS TESTS CONT.
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systems to determine camshaft and crankshaft
position. This enables the ECU to know the
optimum time to fire the ignition coil, and turn on the
fuel injectors. This test checks for proper switching
action in any Hall Effect sensor, Ignition, RPM,
Crankshaft, etc..
Refer to your service manual for the best procedure
for your specific sensor. Some can stay in the
vehicle for testing. The following will be for testing
the sensor in the vehicle.
1. Insert BLACK test lead into COM test lead jack
2. Insert RED test lead into test lead jack.
3. Add the alligator clip to the BLACK probe and
clip it to the Negative (-) post on the battery.
4. Turn the meters range selector to 20V DC.
5. Turn the ignition key on, KOEO.
6. Touch the RED test probe to the three pins of
the sensor. Find the Signal, Supply, and Ground
Pins. Back probing may be necessary to avoid
piercing the wiring.
• Ground reading should be the same voltage as
the ground.
• Supply wire reading should be the same voltage
as the input source.
• Signal wire reading should be 0 or the same
voltage as the input source. This will cycle or toggle
high and low as the shutter rotates.
7. Slide a flat blade of iron or magnetic steel between
sensor and magnet or have a helper crank the
engine and watch the meter display. Record the
results and compare to manufacturer’s specifications.
• A good sensors meter voltage will toggles from as
steel blade is inserted and removed.
• A bad sensors meters voltage will have no change
as steel blade is inserted and removed.
Fuses/Switches
This test checks to see if a switch Opens and
Closes properly and if a fuse is blown.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn meter range selector to function.
4. Add alligator clips and connect BLACK clip to
one side of switch.
5. Connect RED clip to other side of switch.
6. Listen for a tone, if you hear a tone he switch is
closed. If you don’t hear tone the switch is open.
7. Flip the switch on and off, listen for the tone. The
tone should react as you flip the switch on and off.
To test fuses touch the RED and BLACK test leads
to opposite ends of the fuse, listen for tone.
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FUSE/SWITCH/SOLENOID TESTS
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If you hear a tone the fuse is good. If there is no
tone the fuse is blown and needs to be replaced.
Solenoids/Relays
This test checks the solenoid or relay for a broken
internal coil. Typically a resistance of 200Ω or less is
present in a good solinoid/relay. If a high resistance is
detected the unit has break in the coil and is bad.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn the meters range selector to 200Ω function.
If the meter over ranges, turn the meters range
selector to next higher range.
4. Add the alligator clips and connect BLACK
clip to one side of coil.
5. Connect RED clip to other side of coil.
View results on display. If the solenoid/relay coil
resistances is 200Ω or less, the unit should be good.
Refer to vehicle service manual for your vehicles
resistance range.
• A good Solenoid/Relay Coil displays results within
manufacturer’s specification.
• A bad Solenoid/Relay Coil displays results not
within manufacturer’s specifications. If the display
reads over range, that indicating an open circuit or
defective Solenoid/Relay
Distributor Cap/Rotor Resistance
This test checks for open circuits or high
resistance in the distributor cap and rotor if your
vehicle is so equipped.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn meters range selector to 200 Ω range.
4. For the distributor cap test connect the test leads
to opposite ends of the distributor cap. One into the
top center of the cap (coil wire position). The other
on lead touches the inside center of the cap, view
the displayed results. General resistance should be
5K – 10K. Refer to vehicle service manual for your
vehicles resistance range.
5. For the rotor test connect the test leads to opposite
ends of the rotor. One to the top metal contact, and
the other to the extended metal finger contact.
General resistance should be 0.1 Ω or less. Refer
to vehicle service manual for your vehicles
resistance range.
Variable Reluctance Sensor
A variable reluctance sensor is a transducer that,
detects the change in presence or proximity of
FUSE/SWITCH/SOLENOID TESTS CONT.
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IGNITION SYSTEM TESTS
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ferrous objects. Reluctance sensor are used
whenever the vehicle’s ECU needs to know speed
and/or the position of a rotating object. In ignition
systems, it’s used to determine camshaft and
crankshaft position. This tells the vehicle ECU when
to fire the ignition coil and turn on the fuel injectors.
Speed sensors are another type of reluctance
sensor used in transmissions to measure the
rotational speed of shafts. These sensors help the
ECU to determine when to shift from one gear to
the next.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Add the alligator clips and connect the RED
clip to either pin on the Variable Reluctance Sensor.
4. Connect the BLACK clip to the remaining pin.
5. Turn the meters range selector to largest 2K Ω
range. View and record the reading on the display.
6. Now watch the meter while flexing the sensor
wires from the harness connection to the sensor.
Common resistance range is 100 to 1K Ω , refer to
your service manual for resistance range.
• A good sensors display reading will fall within
manufacturer’s specification. There is no erratic
changes in the display readings, results are steady
while sensor wires are flexed.
• A bad sensors display reading changes when the
wiring is flexed, or the reading is not within
manufacturers specifications.
Crankshaft Timing Sensor
The Crankshaft timing sensor is typically located in
the front of the crankshaft to trigger the ignition
system. This sensor consists of a single Hall Effect
magnetic switch activated by 3 vanes on the
crankshaft damper and pulley assembly. This
sensor sends a signal that feeds timing and RPM
information to the DIS and EPU.
To test if it your crankshaft position sensor is working
properly, you need to test for a voltage output.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
For this test you’ll need to back probe or add jumper
leads from the two pin in the harness.
3. Turn the meters range selector to 2V AC range.
4. Crank the engine, view and record the reading
displayed. A normal reading would be at or near .2
volts. Refer to vehicles service manual for
recommended voltage outputs.
Some reference manuals states a resistance
value, if so you can check the sensor without
cranking the engine.
IGNITION SYSTEM TESTS CONT.
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1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn the meters range selector to the 20K Ω range.
Refer to vehicles service manual for recommended
resistance outputs.
If the test results are within specifications, you
should check the sensor’s electrical connector and
the wiring harness. The trigger wheel located on the
crankshaft or damper could have damaged or
missing teeth. Any of these components could
trigger a CKP sensor to trouble code. Completing
the above tests thoroughly will let you know if the
crankshaft position sensor is working or not.
Pick-up Coil Resistance
The resistance test checks for open circuits or high
resistance. The voltage test compares voltage
output to resistance.
1. Insert the BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn meters range selector to 200 Ω range.
4. Connect the RED and BLACK test leads to the
pick-up coil leads from the distributor. View the
displayed results.
The majority of the pick-up coils will test between
500 - 1500 Ω ’s resistances. Refer to vehicle service
manual for your vehicles resistance range.
5. Set range selector to AC volts. Crank the engine 10
– 15 seconds, view the voltage results on the display.
Resistance on a good pick-up coil will match the AC
output voltage. For example 950 Ω would equal
950mV output. Resistance can be good but voltage
low if the magnet has lost magnetism or if the
reluctor is too far from the stator.
Ignition Coil
The ignition coil is designed to transform the
battery’s low voltage to 30,000 volts to bridge the
spark plugs and ignite the fuel. Coils consist of a
laminated iron core surrounded by two coils of
copper wire. The Primary winding has just a few
turns of heavy wire. The Secondary winding has
thousands of turns of smaller wire. Today’s vehicle
uses one ignition coil for each cylinder called COP,
or coil on plug. This improvement system eliminates
the fault-prone spark plug cables and a distributor to
route the high voltage pulses. This test measures
the resistance across the primary and secondary
coils of the ignition coil. This test can be used for
distributor less ignition systems (DIS) providing the
primary and secondary ignition coil terminals are
easily accessible.
For testing the PRIMARY SIDE of the ignition coil
the engine must be cool and off. You’ll need to
IGNITION SYSTEM TESTS CONT.
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identify both the primary ignition coil terminals, (+)
positive and the (-) negative terminals. Once
identified disconnect them from the coil. It’s
recommended to mark the wires if they’re not color
coded, red (+) and black (-). Next remove the
center high tension lead that goes to the distributor.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Turn the meters range selector to the 200Ω
range. Because of the sensitivity of this test touch
the two probes of the test leads together. View the
reading on the display and record the resistance
value.
4. Add the alligator clips and connect the RED
clip to primary ignition coil positive (+) terminal.
5. Connect the BLACK clip to primary ignition coil
negative (-) terminal.
View the reading on the display, subtract the test
lead resistance value from above. Record this final
figure. If your vehicle has DIS, repeat the above
steps for each ignition coil and record the results.
Refer to your service manual for your vehicles
primary ignition coils resistance values.
• A common range for the primary side of the coil
is <2.0Ω.
For testing the SECONDARY SIDE of the ignition
coil, meter connections remain the same.
1. Turn the meters range selector to the 200KΩ
range .
2. Remove the alligator clip from the RED test
lead, and move the probe to the secondary ignition
coil terminal. Typically that’s the tower where the
high tension lead was plugged into.
3. Connect the BLACK clip to primary ignition coil
negative (-) terminal.
View and record the reading. If the vehicle has DIS,
repeat above steps for each coil, record the results.
• A common range for the secondary side of the coil
is 6 to 35KΩ.
Refer to your service manual for your vehicles
secondary ignition coils resistance values.
Because heat can affect resistance levels, repeat
the above tests with the engine at normal operating
temperature. Testing the coil hot helps to diagnosing
intermittent ignition system problems. Just be
cautious, the engine parts will be hot, gloves are
recommended.
• A good Ignition Coil Resistance readings were
within manufacturer’s specification.
Primary side of the coil is <2.0Ω.
Secondary side of the coil range is 6 to 35KΩ.
• A bad Ignition Coil Resistance readings were not
within manufacturer’s specification.
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Primary side of the coil is >2.0Ω.
Secondary side of the coil range is on <6 or >35KΩ.
Coil Switching ON/OFF
The primary circuit is driven by closing a switch to
ground, which allows current to flow from the power
supply through the primary. This test checks if the
negative terminal of the primary ignition coil is
getting switched ON and OFF. The signal comes
from the ignition module, and the crankshaft
position sensors. The ON/OFF signal from the
ignition coil is where the Tach gets its RPM
information. If the test vehicle cranks but won’t fire,
this test and fuel delivery is a good place to start.
1. Insert BLACK test lead into COM test lead jack.
2. Insert RED test lead into test lead jack.
3. Add the alligator clips and connect the RED
clip to the negative side of the primary ignition coil.
Refer to your service manual for the primary ignition
coil location.
4. Connect the BLACK clip to a good body ground.
Vehicle with DIS (Distributorless Ignition System),
you’ll need to identify the Tachometer sign wire that
goes from the DIS module to the ECU. Refer to
your vehicle service manual for the location.
5. Connect the RED test probe to the TACH signal
wire, either back probe or pierce the wire.
6. Use the alligator clips and connect BLACK
clip to a good body ground.
7. Turn the meters range selector to the RPM
settings, choice the range that coincides with the
vehicles cylinder count. View the reading on the
display while engine is cranking. Use a helper to
turn the key, or use a remote starter switch, (part
number W80586). A common meter RPM reading
is >20 but <280. Refer to the service manual for
your vehicles cranking RPM range.
• A good Switching Coils RPM reading should have a
value consistent with manufacturer’s specifications.
• A bad Switching Coil will display 0 RPM’s meaning
the coil is not switched ON and OFF.
Possible items to check for would be bad or shorted
wiring, or bad camshaft/crankshaft sensors.
Ignition Wires
OEM type plug wires are usually have a carbon
fiber core that helps minimize RF noise (Radio
noise). The drawback to carbon fiber is it’s a higher
resistance wire. This resistance reduces the amount
of electrical charge that can be delivered to the
spark plug. A hot spark generated the proper bridge
on the plug electrode to burn a full cylinder of fuel.
Use the following steps to test the resistance of
ignition wires, flex the wire while testing for breaks
in the carbon fibers. This test can be used for DIS.
IGNITION SYSTEM TESTS CONT.
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Test the Coil-On-Plug Insulators for breaks and
those systems that mount their ignition coils away
from the spark plugs.
1. Pull and test the ignition wires one at a time.
Avoid the confusion pulling all the wires without
marking where they go.
If possible use a spark plug boot puller, (part
number W80531) to remove the boot and wire. It’s
best to twist the boot a quarter turn both directions
prior to pulling to break the seal.
2. Once removed, look for cracks, burns, or bad ends.
NOTE: Early Chryslers used a plug wire that had
positive-locking terminal electrodes. To pull the
wires the distributor cap needs to be removed. The
release is on the underside of the Dodge Omni, and
the Plymouth Horizon distributor caps.
3. Insert BLACK test lead into COM test lead jack.
4. Insert RED test lead into test lead jack.
5. Add the alligator clip to the RED test probe only,
connect it to the distributor side of the plug wire.
6. Connect the BLACK test probe into the spark
plug boot at the other end of the wire. Be sure it
contacts the metal electrode connector.
7. Turn meters range selector to the 200KΩ range.
8. View the meter while holding and bending the
wire in several places. Over time with heat and
vibration the carbon fibers tend to loosen which
degrades the conduction.
Commonly the resistance levels range from 4KΩ to
40KΩ. The resistance value is directly affected by
the length of each plug wire, averaging 8KΩ to
10KΩ per foot. Refer to vehicle service manual for
your vehicles resistance range.
• A good Ignition Wire will have no change while
flexing and will meet manufacturer’s specification.
• A bad Ignition Wire reading will be erratic while the
wire is flexed, or the readings won’t be within
manufacturer’s specification.
C3 Meter Control Solenoid
Today’s emission requirements have forced auto
makers to move away from the carbureted fuel
delivery systems. Starting in the early 80s’ auto
makers began using electronically controlled
carburetors to lower vehicle emissions. As emission
requirements got tougher the introduction of
computer commanded fuel injection was introduced.
With the reduced emissions, and the benefit of
increased performance, fuel injection was the future
of fuel delivery. Early GM vehicles used the fuel
mixture control solenoid, these solenoids can be
tested with a digital multimeter that offers a Dwell
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FUEL SYSTEM TESTS
13

measurement. The MC solenoid’s purpose is to
maintain an air/fuel ratio of 14.7 to 1.
This test can verify if the solenoid dwell is varying as
designed. This test is very detailed and you need to
pay close attention to the shop manual instructions.
Visit this web address http://s7d9.scene7.com/is/
content/GenuinePartsCompany/1787689pdf?$P
DF$ or use a shop manual for the complete test
procedures for adjusting a Lean/Rich fuel mixtures.
Refer to vehicle service manual for the specific
meter test connection points.
1. The engine needs to be running and at normal
operating temperature.
2. Turn the meters range selector to the 6 cyl.
Dwell position for all GM vehicles with MC solenoids.
3. The engine idle needs to be at 3000 RPM.
Use the reference web site, or shop manual for the
procedure to run the engine both RICH and LEAN.
View the meter display, the Dwell values should vary
from 10° to 50° as vehicle runs from rich to lean.
Measuring Fuel Injector Resistance
Fuel injectors are basically an ON/OFF switch.
Very similar to solenoids, they contain a coil that is
controlled by the ECU. If your engine is running
rough, there may be an issue with the vehicle’s fuel
delivery system. Having a faulty injector can cause
one or more cylinders to not ignite fully. The ECU
directs the injector to deliver precise amounts of fuel
into each cylinder, regardless of the engines RPMs.
An injector fires millions of times over its life span.
Eventually they can wear out or clog up, preventing
the engine from firing properly. To determine if the
injector is operating properly the resistance of the
internal coil is tested. Testing this resistance reading
will advise if you have an open circuit, or if the coil
is shorted. Its best if you have the specific injector
manufactures rated resistance. Some of the more
common manufacturers of fuel injectors are Bosch,
Siemens, Deka, Continental, Lucas, Japanese
Electronics Corp. (JECS), and Denso.
Injector Test
Some engines have plastic panels that need to be
removed before you can access the injectors. They
are typically secured by bolts and can be removed
with a basic socket set including an extension.
1. Testing the Injector, make sure the key is off, no
power is needed for this test.
2. Remove the injector wiring harness. Be cautious,
the harness has slide lock that you need to move
before you can press on the tabs to remove the
wiring harness.
3. Insert BLACK test lead into COM test lead jack.
FUEL SYSTEM TESTS
4. Insert RED test lead into test lead jack.
5. Turn the meters range selector to the 200Ω setting.
Because of the sensitivity of this test touch the two
probes of the test leads together. View the reading on
the display and record the resistance value.
6. Add the alligator clips and connect the RED
clip to a single prong inside the injector’s connector.
7. Connect the BLACK clip to the other prong, be
sure the two clips don’t touch.
8. View the reading on the display, subtract the test
lead resistance value from above. Record this final
figure.
9. Repeat the above steps for each injector and
record the results. They should all have a resistance
within half an ohm from each other. Any major
difference and that injector should be inspected to
make sure its firing correctly. If the resistance of the
injector coil is within manufacturer’s specifications,
the fuel injector could still be defective. It is possible
that the fuel injector is clogged or dirty and that is
causing your drivability problem.
High impedance injectors are the most common on
vehicles today, they will range from 12 to 17 ohms.
Low impedance injectors are found on high
performance and larger injectors. They have much
lower resistance, typically around 2-5 ohms.
• A good Injectors Coil resistance is within
manufacturers specifications.
• A bad Injectors Coil resistance is not within
manufacturers specifications.
Injector Wiring Harness Test
1. Testing the Injectors wiring, turn the key to the
ON position, KOEO.
2. Insert BLACK test lead into COM test lead jack.
3. Insert RED test lead into test lead jack.
4. Turn the meters range selector to the 20VDC
setting.
5. Add the alligator clip to the BLACK test lead
only, clip to a good body ground.
6. Touch the RED test leads probe to a single
prong inside the injectors wiring harness. (Not the
injectors, but the harness that plugs into the
injectors connection). One prong will be the ground
and your meter will read 0 volts. The other prong is
the power source for the injector and should read
around 12 volts.
7. View and record the reading on the display.
8. Leave the ground lead in position and repeat the
above steps for each injectors wiring harness and
record the results. Your results should all be around
12 volts. A lower reading means theres excess
resistance in the injectors wiring somewhere.
• A good Injector Harness voltage is within
manufacturers specifications.
• A bad Injectors Harness voltage is not within
manufacturers specifications.
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Overrange Indication
If the 1 or -1 appears on the left side of the display the multimeter is overranged. This is when a range
has been selected that is lower than what the meter is currently reading. Increase the range until this
disappears. If it doesn’t, then the value being measured is too large for the meter to measure.
Zero Adjustment
There is no meter adjustments, this unit will automatically zero on the Volts, Amps and RPM functions.
Automatic Polarity
If the meter displays a minus (-) symbol on the DC volts or DC amp functions then the test leads are reversed.
Alligator Clip Adapters
Some meter tests and measurements are better done by using the alligator clips instead of just the
test probes. The clip provided just push onto the test probes.
Low Battery
When the 9v battery needs to be replaced a battery symbol will appears in the lower left corner of the display.
Battery Replacement
Turn meter OFF and remove test leads.
Remove screw from battery cover, remove battery cover, and battery
Install a new 9 Volt battery and re-assemble meter.
Fuse Replacement
Turn meter OFF and remove test leads.
Remove rubber holster and remove screw from battery cover, remove battery cover, and battery.
Remove screws from back of multimeter, remove back cover and remove fuse.
Replace fuse with same size and type as originally installed, re-assemble meter.
Fuse: 10A, 250V
Maintenance
Periodically wipe the case with a damp cloth, do not use abrasives or solvents. Do not subject the
meter to extreme heat or cold temperatures. Keep test probes away from extreme such as vehicle
exhaust manifolds.
MAINTENANCE & TROUBLESHOOTING
15

LIMITED WARRANTY
PERFORMANCE TOOL extends only the following warranties, and only to original retail
purchasers. These warranties give specific legal rights. Except where prohibited by local law,
the law of the State of Washington governs all warranties and all exclusions and limitations of
warranties and remedies. There may be other rights which vary from state to state.
PERFORMANCE TOOL warrants the product to be free from defects in materials and
workmanship under normal use and service. A defective product may be returned for a free
replacement within 90 days from the date of purchase, provided that product is returned to place
of purchase immediately after discovery of defect. After 90 days and up to 1 year from date of
purchase, PERFORMANCE TOOL will replace at no charge any parts which our examination
shall disclose to be defective and under warranty. These warranties shall be valid only when
a sales receipt showing the date of purchase accompanies the defective product or defective
part(s) being returned. For part(s) after 90 days, please remit your request, postage prepaid to:
PERFORMANCE TOOL, P.O. Box 24086 Seattle, WA 98124
These warranties exclude blades, bits, punches, dies, bulbs, fuses, and other consumables which
must be replaced under normal use and service. These warranties shall not apply to any product
or part which is used for a purpose for which it is not designed, or which has been repaired
or altered in any way so as to affect adversely its performance or reliability, nor shall these
warranties apply to any product or part which has been subject to misuse, neglect, accident or
wear and tear incident to normal use and service.
PERFORMANCE TOOL does not authorize any other person to make any warranty or to assume
any liability in connection with its products.
Except for warranties of title and the limited express warranties set forth above, PERFORMANCE
TOOL makes no express or implied warranties of any kind with respect to its products. In
particular, PERFORMANCE TOOL makes no implied warranty of merchantability and no implied
warranty of fitness for any particular purpose, except that for goods purchased primarily for
personal, family or household use and not for commercial or business use, PERFORMANCE
TOOL makes an implied warranty of merchantability (and, if otherwise applicable, an implied
warranty of fitness for a particular purpose), but only for the particular qualities or characteristics,
and for the duration, expressly warranted above. The laws on limitation of implied warranties may
differ from state to state, so the above limitations may not apply in all cases.
PERFORMANCE TOOL shall not be liable for consequential, incidental or special damages
resulting from or in any manner related to any product, or to the design, use, or any inability to use
the product. The sole and exclusive remedy for a defective product or part shall be the repair, or
replacement thereof as provided above. The laws on limitation of remedies or on consequential,
incidental or special damages may vary from state to state, so the above limitations may not apply
in all cases.
Copyright © 2017 PERFORMANCE TOOL – All rights reserved