Extech Instruments AUT500 User manual

USER GUIDE
Automotive Multimeter
MODEL AUT500

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Introduction
Thank you for selecting the Extech AUT500 Automotive Multimeter. The AUT500 is an Auto Range
Multimeter that measures AC/DC Voltage, AC/DC Current, Resistance, Capacitance, Frequency,
Diode, Continuity, RPM, Dwell, and Duty Cycle. The AUT500 also measures contact temperature via
supplied Thermocouple probe.
The AUT500 features a rugged design for heavy duty use. This device is shipped fully tested and
calibrated and, with proper use, will provide years of reliable service. Please visit our website
(www.extech.com) to check for the latest version of this User Guide, Product Updates, and Customer
Support.
Safety
International Safety Symbols
This symbol, adjacent to another symbol or terminal, indicates the user must refer to the
manual for further information.
This symbol, adjacent to a terminal, indicates that, under normal use, hazardous voltages
may be present
Double insulation
This WARNING symbol indicates a potentially hazardous situation, which if not
avoided, could result in death or serious injury.
This CAUTION symbol indicates a potentially hazardous situation, which if not
avoided, may result damage to the product.
This symbol advises the user that the terminal(s) so marked must not be
connected to a circuit point at which the voltage with respect to earth ground
exceeds (in this case) 600 VAC or VDC.
CAUTIONS
Improper use of this meter can cause damage, shock, injury or death. Read and understand
this user manual before operating the meter.
Always remove the test leads before replacing the battery or fuses.
Inspect the condition of the test leads and the meter itself for any damage before operating the
meter. Repair any damage or replace the unit before use.
Use great care when making measurements if the voltages are greater than 25VAC rms or
35VDC. These voltages are considered a shock hazard.
Always discharge capacitors and remove power from the device under test before performing
Diode, Resistance or Continuity tests.
Voltage checks on electrical outlets can be difficult and misleading because of the uncertainty
of connection to the recessed electrical contacts. Other means should be used to ensure that
the terminals are not "live".
WARNING
CAUTION
MAX
600V

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If the equipment is used in a manner not specified by the manufacturer, the protection provided
by the equipment may be impaired.
This device is not a toy and must not reach children’s hands. It contains hazardous objects as
well as small parts that the children could swallow. In case a child swallows any of them,
please contact a physician immediately
Do not leave batteries and packing material lying around unattended; they can be dangerous
for children if they use them as toys
In case the device is going to be unused for an extended period of time, remove the batteries
to prevent them from training
Expired or damaged batteries can cause cauterization on contact with the skin. Always,
therefore, use suitable hand gloves in such cases
See that the batteries are not short-circuited. Do not throw batteries into the fire.
DANGERS
Engines produce carbon monoxide which is odorless, causes slower reaction time, and can
lead to serious injury. When the engine is operating keep service areas well ventilated or
attach the vehicle exhaust system to the shop exhaust removal system.
Set the parking brake and block the wheels before testing or repairing the vehicle. It is
especially important to block the wheels on front-wheel drive vehicles; the parking brake does
not hold the drive wheels.
Wear an eye shield when testing or repairing vehicles.
Keep the meter away from spark plug and coil wires.
Exceeding the limits of this meter is dangerous. This will expose you to serious or possibly fatal
injury. Carefully read and understand the cautions and the specification limits of this meter.
Avoid electrical shock; do not touch the test leads, tips, or the circuit under test.
Do not try a voltage measurement with the test leads in the 20A or the mA terminal.
Choose the proper range and function for the measurement. Do not try voltage or current
measurements that may exceed the ratings marked on the Function/Range switch or terminal.
When measuring current, connect the meter in series with the load.
Never connect more than one set of test leads to the meter.
Disconnect the live test lead before disconnecting the common test lead.
The mA and the 20A terminals are protected by fuses. To avoid possible injury or damage, use
only in circuits limited to 400mA.

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OVERVOLTAGE CATEGORY III
This meter meets the IEC 610-1-2001 standard for OVERVOLTAGE CATEGORY III. Cat III meters are
protected against overvoltage transients in fixed installation at the distribution level. Examples include
switches in the fixed installation and some equipment for industrial use with permanent connection to
the fixed installation.
METER SAFETY RULES
This meter has been designed for safe use, but must be operated with caution. The rules listed below
must be carefully followed for safe operation.
1. NEVER apply voltage or current to the meter that exceeds the specified maximum:
Input Protection Limits
Function Maximum Input
Voltage DC or V AC
Ohms, Continuity
Diode, Capacitance, Type K Temperature
Frequency, % Duty, Pulse-ms, Dwell
RPM
600V AC or DC
mA AC/DC 400mA 250V
20A AC/DC 20A AC or DC*
* 20A measurements for 30 seconds maximum
Notes: Resistance (Ohms) cannot be measured if voltage is present. Resistance can only be
measured on a non-powered circuit
2. USE EXTREME CAUTION when working with high voltages.
3. DO NOT measure voltage if the voltage on the "COM" input jack exceeds 600V above earth
ground.
4. NEVER connect the meter leads across a voltage source while the function switch is in the
current, resistance, or diode mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies and disconnect the power when making
resistance or diode tests.
6. ALWAYS turn off the power and disconnect the test leads before opening the covers to replace
the fuse or batteries.
7. NEVER operate the meter unless the back cover and the battery and fuse covers are in place
and fastened securely.

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Controls and Jacks
1. LCD display
2. MODE button
3. HOLD button
4. RANGE button
5. PEAK button
6. MAX-MIN button
7. Backlight button
8. Function switch
9. 20A input jack
10. 400mA input jack
11. Positive input jack
12. COM input jack
Note: Tilt stand, test lead holders, and battery compartment are located on rear of unit. Fuses are
accessible by removing the meter’s back cover, instructions provided later in this guide.

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Symbols and Annunciators
•))) Continuity
Diode test
Battery status
n nano (10-9) (capacitance)
µ micro (10-6) (amps, cap)
m milli (10-3) (volts, amps, milli-seconds: ms)
A Amps
k kilo (103) (ohms)
F Farads (capacitance)
M mega (106) (ohms)
 Ohms (resistance, continuity)
Hz Hertz (frequency)
V Volts
% Percent
REL Relative (unused in this model)
AC Alternating current
DC Direct current
MAX Highest reading
MIN Lowest reading
ºF Degrees Fahrenheit
ºC Degrees Centigrade
Pmax Maximum peak
Pmin Minimum peak
RPM Rotations per minute
Trig Positive (+) or Negative (-) Trigger
CYL Cylinder (4, 5, 6, and 8)
Display Hold
x10 Multiply displayed reading by 10
Bargraph
Manual range (top left on LCD)
AUTO Auto range mode
Auto Power OFF icon (middle left on LCD)
Dwell angle icon
H

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Operating Instructions
WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are very dangerous and
should be measured with great care.
1. ALWAYS turn the function switch to the OFF position when the meter is not in use.
2. If “OL” appears in the display during a measurement, the value exceeds the range selected. Change
to a higher range.
NOTE: On some low AC and DC voltage ranges, with the test leads not connected to a device, the
display may show a random, changing reading. This response is normal and is caused by the high-
input sensitivity. The reading will stabilize and give a proper measurement when connected to a
circuit.
DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC voltages if a motor on the circuit is being switched ON or OFF.
Large voltage surges may occur that can damage the meter.
1. Set the function switch to the ‘V’ position.
2. Press the MODE button to indicate “DC” on the display.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive Vjack.
4. Touch the black test probe tip to the negative side of the circuit.
Touch the red test probe tip to the positive side of the circuit.
5. Read the voltage in the display as numerical digits and as bar-graph
representation.

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AC VOLTAGE MEASUREMENTS
WARNING: Risk of Electrocution. The probe tips may not be long enough to contact the live parts
inside some 240V outlets for appliances because the contacts are recessed deep in the outlets. As
a result, the reading may show 0 volts when the outlet actually has voltage on it. Make sure the
probe tips are touching the metal contacts inside the outlet before assuming that no voltage is
present.
CAUTION: Do not measure AC voltages if a motor on the circuit is being switched ON or OFF.
Large voltage surges may occur that can damage the meter.
1. Set the function switch to the ‘V’ position.
2. Press the MODE button to indicate “AC” on the display.
3. Insert the black test lead banana plug into the negative COM jack.
Insert red test lead banana plug into the positive Vjack.
4. Touch the black test probe tip to the neutral side of the circuit.
Touch the red test probe tip to the “hot” side of the circuit.
5. Read the voltage in the display as numerical digits and as bar-graph
representation.
DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 20A scale for longer than 30 seconds.
Exceeding 30 seconds may cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM jack.
2. For current measurements up to 400mA DC, set the function switch to the
mA position and insert the red test lead banana plug into the 400mA jack.
3. For current measurements up to 20A DC, set the function switch to the
20A range and insert the red test lead banana plug into the 20A jack.
4. Press the MODE button to indicate “DC” on the display.
5. Remove power from the circuit under test, then open up the circuit at the
point where you wish to measure current.
6. Touch the black test probe tip to the negative side of the circuit.
Touch the red test probe tip to the positive side of the circuit.
7. Apply power to the circuit.
8. Read the current in the display as numerical digits and as bar-graph
representation.

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AC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 20A scale for longer than 30 seconds.
Exceeding 30 seconds may cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM jack
2. For current measurements up to 400mA AC, set the function switch
to the mA position and insert the red test lead banana plug into the
400mA jack.
3. For current measurements up to 20A AC, set the function switch to
the 20A range and insert the red test lead banana plug into the 20A
jack.
4. Press the MODE button to indicate “AC” on the display.
5. Remove power from the circuit under test, then open up the circuit
at the point where you wish to measure current.
6. Touch the black test probe tip to the neutral side of the circuit.
Touch the red test probe tip to the “hot” side of the circuit.
7. Apply power to the circuit.
8. Read the current in the display as numerical digits and as bar-graph
representation.
RESISTANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to the unit under test and discharge all
capacitors before taking any resistance measurements. Remove the batteries and unplug the line
cords.
1. Set the function switch to the Ω position.
2. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive jack.
3. Press the MODE button to indicate “"on the display.
4. Touch the test probe tips across the circuit or part under test. It is best
to disconnect one side of the part under test so the rest of the circuit
will not interfere with the resistance reading.
5. Read the resistance in the display.

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CONTINUITY CHECK
WARNING: To avoid electric shock, never measure continuity on circuits or wires that have
voltage on them.
1. Set the function switch to the Ωposition. Refer to the Resistance measurement diagram
above for reference.
2. Insert the black lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive jack.
3. Press the MODE button to indicate “ " on the display
4. Touch the test probe tips to the circuit or wire you wish to check.
5. If the resistance is less than approximately 35, the audible signal will sound. If the circuit is open,
the display will indicate “OL”.
DIODE TEST
1. Set the function switch to the Ωposition.
2. Insert the black test lead banana plug into the negative
COM jack and the red test lead banana plug into the
positive Vjack.
3. Press the MODE button to indicate and Von the
display.
4. Touch the test probes to the diode under test. Forward
voltage will typically indicate 0.400 to 0.700V. Reverse
voltage will indicate “OL”. Shorted devices will indicate
near 0V and an open device will indicate “OL” in both
polarities.
CONTACT TEMPERATURE MEASUREMENTS (TYPE K)
1. Set the function switch to the Type K ºC or ºF position.
2. Insert the Temperature Probe into the input jacks, making sure to observe the correct polarity.
3. Touch the Temperature Probe tip to the part under test. When the reading stabilizes (after
approximately 30 seconds) remove the probe tip from the surface
under test.
4. Read the temperature in the display as numerical digits and as
bar-graph representation.
Note: The temperature probe is fitted with a type K mini connector. A
mini connector to banana connector adaptor is supplied for
connection to the meter’s input banana jacks.