PleasureCraft Engine Group 5.0L User manual

MEFI 4 / 4B
DIAGNOSTIC
MANUAL
5.0/5.7/6.0/8.1L
L510005P 11/05

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Marine Electronic Fuel Injection (MEFI 4 / 4B)
Contents
Section 1 - General Information........................................................................................................................Page 1-1
Section 2 - ECM and Sensors ..........................................................................................................................Page 2-1
Section 3A - Fuel Metering System (5.0/5.7L)................................................................................................Page 3A-1
Section 3B - Fuel Metering System (6.0L) .....................................................................................................Page 3B-1
Section 3C - Fuel Metering System (8.1L) .................................................................................................... Page 3C-1
Section 4A - Ignition System (5.0/5.7L) ..........................................................................................................Page 4A-1
Section 4B - Ignition System (6.0/8.1L) ..........................................................................................................Page 4B-1
Section 5 - Diagnosis........................................................................................................................................Page 5-1
Section 6 - PCV System ...................................................................................................................................Page 6-1
Section 7 - Symptoms.......................................................................................................................................Page 7-1
Section 8 - Master Specifications......................................................................................................................Page 8-1

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5.0/5.7/6.0L/8.1L General Information 1 - 1
MEFI 4 - PCM
Marine Electronic Fuel Injection (MEFI)
Section 1
General Information
Contents
Clearing Diagnostic Trouble Codes (Scan) ......Page 5
Non-Scan Diagnosis of Driveability Concerns
(No DTCs Set) .................................................Page 5
Aftermarket (Add-On) Electrical and
Vacuum Equipment...........................................Page 5
Use of Circuit Testing Tools...............................Page 5
Tools Needed to Service the System ...............Page 5
Service Precautions..........................................Page 6
Test Light Amperage Draw Test........................Page 6
Special Tools (1 of 3) .......................................Page 7
Special Tools (2 of 3) .......................................Page 8
Special Tools (3 of 3) .......................................Page 9
Abbreviations.......................................................Page 10
Diagnosis .............................................................Page 11
On-Board Service................................................Page 11
Wiring Harness Service..................................Page 11
Wiring Connector Service...............................Page 12
Metri-Pack Series 150 Terminals..............Page 12
Weather-Pack Connectors........................Page 13
Micro-Pack 100/W Series Connectors .....Page 14
General Description .............................................Page 2
Visual/Physical Inspection ...............................Page 2
Basic Knowledge and Tools Required............. Page 2
Electrostatic Discharge Damage ..................... Page 2
Engine Wiring................................................... Page 2
Engine Control Module (ECM)
Self-Diagnostics............................................... Page 2
Malfunction Indicator Lamp (MIL) ...................Page 2
Intermittent Malfunction Indicator Lamp
(MIL) .........................................................Page 3
Reading Diagnostic Trouble Codes
(DTCs) ...................................................... Page 3
Service Mode ............................................ Page 3
Normal Mode.............................................Page 3
MEFI On-Board Diagnostic (OBD)
System Check..................................................Page 3
DLC Scan Tools............................................... Page 3
Scan Tool Use With Intermittents.....................Page 4
How Diagnostic Trouble Codes Are Set........... Page 4
Clearing Diagnostic Trouble Codes
(Non-Scan) ...................................................... Page 4

1 - 2 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
General Description
Visual and Physical Inspection
Important: This visual and physical inspection is
very important. Perform this inspection carefully and
thoroughly. Perform a careful visual and physical
inspection when performing any diagnostic procedure.
This can often lead to repairing a problem without further
steps. Use the following guidelines when performing a
visual and physical inspection:
• Inspect all vacuum hoses for the following
conditions:
–Correct routing
–Pinches
–Cuts
–Disconnects
• Inspect all wires in the engine compartment for the
following conditions:
–Proper connections
–Burned or chafed spots
–Pinched wires
–Contact with sharp edges
–Contact with hot exhaust manifolds
Basic Knowledge andTools Required
To use this manual most effectively, a general
understanding of basic electrical circuits and circuit
testing tools is required.You should be familiar with wiring
diagrams, the meaning of voltage, ohms, amps and the
basic theories of electricity. You should also understand
what happens if a circuit becomes open, shorted to ground
or shorted to voltage.
To perform system diagnostics, several special tools and
equipment are required. Please become acquainted with
the tools and their use before attempting to diagnose the
system. Special tools that are required for system service
are illustrated in this section.
Electrostatic Discharge Damage
Electronic components used in control systems are often
designedto carry verylowvoltage,and are very susceptible
to damage caused by electrostatic discharge.It is possible
for less than 100 volts of static electricity to cause damage
to some electronic components. By comparison, it takes
as much as 4,000 volts for a person to feel the zap of
a static discharge.
There are several ways a person can become statically
charged. The most common methods of charging are by
friction and by induction.An example of charging by friction
is a person sliding across a seat, in which a charge of as
much as 25,000 volts can build up. Charging by induction
occurs when a person with well insulated shoes stands
near a highly charged object and momentarily touches
ground. Charges of the same polarity are drained off,
leaving the person highly charged with the opposite
polarity. Static charges of either type can cause damage.
Therefore, it is important to use care when handling and
testing electronic components.
EngineWiring
When it is necessary to move any of the wiring, whether
to lift wires away from their harnesses or move harnesses
to reach some component, take care that all wiring is
replaced in its original position and all harnesses are
routed correctly. If clips or retainers break, replace them.
Electrical problems can result from wiring or harnesses
becoming loose and moving from their original positions,
or from being rerouted.
Engine Control Module (ECM) Self-
Diagnostics
The Engine Control Module (ECM) performs a continuous
self-diagnosis on certain control functions.This diagnostic
capability is complemented by the diagnostic procedures
contained in this manual. The ECM’s language for
communicating the source of a malfunction is a system of
DiagnosticTrouble Codes (DTC’s).The DTC’s are two digit
numbers that can range from 12 to 81.When a malfunction
is detected by the ECM, a DTC is set and the Malfunction
Indicator Lamp (MIL) is illuminated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) is part of the Marine
Diagnostic Trouble Code (MDTC) tool, or it can be a dash
mounted warning light on some boat models.
•If present, it informs the operator that a problem has
occurred and that the boat should be taken for service
as soon as reasonably possible.
•It displays DTC’s stored by the ECM which help the
technician diagnose system problems.
As a bulb and system check, the light will come “ON” with
the key “ON,” engine “OFF.” When the engine is started,
the light will turn “OFF.” If the light remains “ON,” the
self-diagnostic system has detected a problem. If the
problem goes away, the light may go out, but a DTC will
remain stored in the ECM.
When the light remains “ON” while the engine is running,
or when a malfunction is suspected due to a driveability
problem, the MEFI “On-Board Diagnostic (OBD) System
Check” must be performed as the first step.These checks
will expose malfunctions which may not be detected if other
diagnostics are performed prematurely.

5.0/5.7/6.0L/8.1L General Information 1 - 3
MEFI 4 - PCM
Figure 1-1 - Marine Data Link Connector (DLC)
A B C D E
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K J H G F
A
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B
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MS 13554
DATA LINK CONNECTOR (DLC)
6-18-93
times. At the end of the DTC’s, the ECM will simply go
back and start over with flashing DTC 12.
Service Mode
When the DTC tool is installed at the DLC and “service
mode” or “ON” is selected, the system will enter what is
called the “Service Mode.” In this mode, the ECM will:
•Display a DTC 12 by flashing the MIL, indicating that
the diagnostic system is working.
•Display any stored DTC’s by flashing the MIL. Each
DTC will be flashed two times, then DTC 12 will be
flashed again.
Normal Mode
When the DTC tool is in the “normal mode” or “OFF,” it has
no affect on the engine operation.
MEFI On-Board Diagnostic (OBD) System
Check
After the visual/physical inspection, the “On-Board
Diagnostic (OBD) System Check”is the starting point for all
diagnostic procedures. Refer to Diagnosis section.
The correct procedure to diagnose a problem is to follow
two basic steps:
1. Are the on-board diagnostics working? This is
determined by performing the “On-Board Diagnostic
(OBD) System Check.” Since this is the starting point
for the diagnostic procedures, always begin here. If
the on-board diagnostics are not working, the OBD
system check will lead to a Diagnostic Procedure
in the Diagnosis section to correct the problem. If
the on-board diagnostics are working properly, the
next step is:
2. Is there a DTC stored? If a DTC is stored, go directly to
the number DTC procedure in the Diagnosis section.
This will determine if the fault is still present.
DLC ScanTools
TheECM can communicatea variety of informationthrough
the DLC.This data is transmitted at a high frequency which
requires a scan tool for interpretation.
With an understanding of the data which the scan tool
displays, and knowledge of the circuits involved, the scan
tool can be very useful in obtaining information which
would be more difficult or impossible to obtain with other
equipment.
Ascan tooldoes not makethe use of Diagnostic Procedures
unnecessary, nor do they indicate exactly where the
problem is in a particular circuit. Some Diagnostic
Procedures incorporate steps with the use of a scan
tool (scan diagnostics), or with the DTC tool (non-scan
diagnostics).
a hand-held diagnostic scanner, plugged into the DLC.
Once the DTC tool has been connected, and “service
mode” or “ON” selected, the ignition switch must be moved
to the key “ON,” engine “OFF” position. At this point, the
MIL should flash DTC 12 two times consecutively. This
would be the following flash sequence: “flash, pause,
flash-flash, long pause, flash, pause, flash-flash.” DTC 12
indicates that the ECM’s diagnostic system is operating.
If DTC 12 is not indicated, a problem is present within
the diagnostic system itself, and should be addressed
by consulting the “On-Board Diagnostic (OBD) System
Check” in the Diagnosis section.
Following the output of DTC 12, the MIL will indicate a
DTC two times if a DTC is present, or it will continue to
flash DTC 12. If more than one DTC has been stored in
the ECM’s memory, the DTC’s will be flashed out from the
lowest to the highest, with each DTC being flashed two
Intermittent Malfunction Indicator Lamp (MIL)
In the case of an “intermittent” problem, the Malfunction
Indicator Lamp (MIL) will light for 10 seconds, and then
go out. However, the corresponding DTC will be stored
in the memory of the ECM. When DTC’s are set by an
intermittent malfunction, theycould behelpful indiagnosing
the system.
If an intermittent DTC is cleared, it may or may not reset.If
it is an intermittent failure, consult the “Diagnostic Aids” on
thefacingpage of the correspondingDiagnostic Procedure.
Symptoms section also covers the topic of “Intermittents.”
A physical inspection of the applicable sub-system most
often will resolve the problem.
Reading DiagnosticTrouble Codes (DTC’s)
The provision for communicating with the ECM is the Data
Link Connector (DLC) (Figure 1-1). It is part of the MEFI
engine wiring harness, and is a 10-pin connector, which
is electrically connected to the ECM. It is used in the
assembly plant to receive information in checking that the
engine is operating properly before it leaves the plant.The
DTC(s) stored in the ECM’s memory can be retrieved two
different ways. One way is with a Diagnostic Trouble Code
(DTC) tool.The other way is through a scan tool,

1 - 4 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX
XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX
0 VOLTS
5 VOLTS
6-5-93
MS 13553
V
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L
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TYPICAL SENSOR RANGE
“WINDOW”
4.6V
0.7V
Figure 1-2 - Example of Sensor Normal Operation
Clearing DiagnosticTrouble Codes (Non-
Scan)
1. Install Diagnostic Trouble Code (DTC) tool.
2. Ignition “ON,” engine “OFF.”
3. Switch DTC tool to “service mode” or “ON.”
4. Move the throttle from 0% (idle) to 100% (WOT) and
back to 0%.
5. Switch DTC tool to “normal mode” or “OFF.” (If this
step is not performed, the engine may not start and
run).
6. Turn ignition “OFF” for at least 20 seconds.
7. Ignition “ON,” engine “OFF.”
8. Switch DTC tool to “service mode” or “ON” and verify
DTC 12 only. Remove DTC tool.
9. If original DTC(s) are still present, check“Notice” below
and repeat the DTC clearing procedure.
10. If new DTC(s) are displayed, perform the OBD system
check.
NOTICE: When clearing DTC’s with or without the use of a
scan tool, the ignition must be cycled to the “OFF” position
or the DTC’s will not clear.
ScanTool Use With Intermittents
The scan tool provides the ability to perform a “wiggle test”
on wiring harnesses or components with the engine not
running, while observing the scan tool display.
The scan tool can be plugged in and observed while
driving the boat under the condition when the MIL turns
“ON” momentarily, or when the engine driveability is
momentarily poor. If the problem seems to be related to
certain parameters that can be checked on the scan tool,
they should be checked while driving the boat. If there
does not seem to be any correlation between the problem
and any specific circuit, the scan tool can be checked on
each position, watching for a period of time to see if there
is any change in the readings that indicates intermittent
operation.
The scan tool is also an easy way to compare the operating
parameters of a poorly operating engine with those of a
known good one. For example, a sensor may shift in value
but not set a DTC.
The scan tool has the ability to save time in diagnosis
and prevent the replacement of good parts. The key to
using the scan tool successfully for diagnosis lies in the
technicians ability to understand the system they are trying
to diagnose, as well as an understanding of the scan tool
operation and limitations. The technician should read the
tool manufacturer’s operating manual to become familiar
with the tool’s operation.
How DiagnosticTrouble Codes (DTC) Are Set
The ECM is programmed to receive calibrated voltage
signals from the sensors. The voltage signal from the
sensor may range from as low as 0.1 volt to as high
as 4.9 volts. The sensor voltage signal is calibrated for
engine application. This would be the sensor’s operating
parameter or “window.” The ECM and sensors will be
discussed further in the ECM and Sensor section.
If a sensor is within its operating or acceptable parameters
(Figure 1-2), the ECM does not detect a problem.When a
sensor voltage signal falls out of this “window,” the ECM
no longer receives a signal voltage within the operating
“window.” When the ECM does not receive the “window”
voltage for a calibratible length of time, a DTC will be
stored. The MIL will be illuminated and a known default
value will replace the sensor value to restore engine
performance.

5.0/5.7/6.0L/8.1L General Information 1 - 5
MEFI 4 - PCM
XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX
XXXXXXXXXXXXXXX DEFAULTXXXXXXXXXXX
------50 -4.2V OUT OF RANGE SENSOR
------150 -1.7V ACTUAL COOLANT TEMPERATURE
HIGH TEMP - 0 VOLTS
LOW TEMP - 5 VOLTS
6-5-93
MS 13552
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Figure 1-3 - Example of Shifted Sensor Operation
Aftermarket (Add-On) Electrical AndVacuum
Equipment
Aftermarket, add-on electrical and vacuum equipment is
defined as any equipment installed on a vehicle after
leaving the factory that connects to the vehicles electrical
or vacuum systems.
Notice: Do not attach add-on vacuum operated
equipment to this engine.The use of add-on vacuum
equipment may result in damage to engine components
or systems.
Notice: Connect any add-on electrically operated
equipment to the vehicle’s electrical system at the battery
(power and ground) in order to prevent damage to the
vehicle.
Add-on electrical equipment, even when installed to
these strict guidelines, may still cause the powertrain
system to malfunction.This may also include equipment
not connected to the vehicle’s electrical system such as
portable telephones and radios.Therefore, the first step
in diagnosing any powertrain problem, is to eliminate all
aftermarket electrical equipment from the vehicle. After
this is done, if the problem still exists, diagnose the
problem in the normal manner.
Use of CircuitTestingTools
Do not use a test lamp in order to diagnose the engine
electrical systems unless specifically instructed by the
diagnostic procedures. Use the J 35616-A connector
test adapter kit whenever diagnostic procedures call for
probing any connectors.
Tools NeededTo ServiceThe System
Refer to Special Tools in this section for engine control
tools for servicing the system.
Clearing DiagnosticTrouble Codes (Scan)
1. Install scan tool.
2. Start engine.
3. Select “clear DTC’s” function.
4. Clear DTC’s.
5. Turn ignition “OFF” for at least 20 seconds.
6. Turn ignition “ON” and read DTC’s. If DTC’s are still
present, check “Notice” below and repeat procedure
following from step 2.
NOTICE: When clearing DTC’s with or without the use of a
scan tool, the ignition must be cycled to the “OFF” position
or the DTC’s will not clear.
Non-Scan Diagnosis Of Driveability
Concerns (No DTC’s Set)
If a driveability concern still exists after following the OBD
system check and reviewing the Symptoms section, an
out of range sensor may be suspected. Because of the
unique design of the MEFI system, the ECM will replace
sensed values with calibrated default values in the case of
a sensor or circuit malfunction. By allowing this to occur,
limited engine performance is restored until the boat
is repaired. A basic understanding of sensor operation
is necessary to be able to diagnose an out of range
sensor.
If the sensor is out of range, but still within the operating
“window”of the ECM, the problem will go undetected by the
ECM and may result in a driveability concern.
A good example of this would be if the coolant sensor was
reading incorrectly and indicating to the ECM that coolant
temperature was at 50°F, but actual coolant temperature
was at 150°F (Figure 1-3). This would cause the ECM to
deliver more fuel than what was actually needed by the
engine. This resulted in an overly rich condition, causing
rough running. This condition would not have caused
a DTC to set, as the ECM interprets this as within the
operating “window.”
To identify a sensor that is out of range, you may unplug
the sensor electrical connector while the engine is running.
After about 2 minutes, the DTC for that sensor will set,
illuminate the MIL, and replace the sensed value with
a calibrated default value. If at that point, a noticeable
performance increase is observed, the non-scan DTC
table for that particular sensor may be followed to correct
the problem.
NOTICE: Be sure to clear each DTC after disconnecting
and reconnecting each sensor. Failure to do so may result
in a misdiagnosis of the driveability concern.

1 - 6 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
Figure 1-4 - Test Light Amperage Draw Test
DC Amps
testlight
*
BATTERY
+
-
If the ammeter indicates less than 3/10 amp(.3A) current flow,
the testlight is
safe to use.
If the ammeter indicates
more than 3/10 amp(.3A) current flow,
the testlight is
not safe to use. I 22307
Service Precautions
The following requirements must be observed when
working on MEFI equipped engines.
1. Before removing any ECM system component,
disconnect the negative battery cable.
2. Never start the engine without the battery being solidly
connected.
3. Never separate the battery from the on-board electrical
system while the engine is running.
4. Never separate the battery feed wire from the charging
system while the engine is running.
5. When charging the battery, disconnect it from the
vehicle’s electrical system.
6. Ensure that all cable harnesses are connected solidly
and the battery connections are thoroughly clean.
7. Never connect or disconnect the wiring harness at the
ECM when the ignition is switched “ON.”
8. Before attempting any electric arc welding on the
vehicle, disconnect the battery leads and the ECM
connector(s).
9. When steam cleaning engines, do not direct the nozzle
at any ECM system components. If this happens,
corrosion of the terminals or damage of components
can take place.
10. Use only the test equipment specified in the diagnostic
procedures, since other test equipment may either give
incorrect test results or damage good components.
11. Allmeasurements usinga multimetermustuse a digital
meter with a rating of 10 megaohm input impedance.
12. When a test light is specified, a “low-power” test light
must be used. Do not use a high-wattage test light.
While a particular brand of test light is not suggested,
a simple test on any test light will ensure it to be safe
for system circuit testing (Figure 1-4). Connect an
accurate ammeter (such as the high-impedance digital
multimeter) in series with the test light being tested,
and power the test light ammeter circuit with the
vehicle battery.

5.0/5.7/6.0L/8.1L General Information 1 - 7
MEFI 4 - PCM
VOLTMETER - Voltage position measures magnitude of
voltage when connected in parallel to an existing circuit.
A digital voltmeter with a 10 megohm input impedance
is used because this type of meter will not load down
the circuit and result in faulty readings. Some circuits
require accurate low voltage readings because they have
a very high resistance.
AMMETER - When used as an ammeter, this meter
accurately measures extremely low current flow. Refer to
meter instructions for more information.
•Selector must be set properly for both function and
range. DC is used for most measurements.
OHMMETER - Measures resistance of circuit directly in
ohms. Refer to meter instructions for more information.
•OL display in all ranges indicates open circuit.
•Zero display in all ranges indicates a short circuit.
•An intermittent connection in a circuit may be indicated
by a digital reading that will not stabilize on the
circuit.
•Range Switch - Automatic and Manual.
200ý - Reads ohms directly
2K, 20K, 200Ký - Reads ohms in thousands
2M, 20M, 200Mý - Reads ohms in millions
VACUUM PUMP WITH GAUGE (20 IN. HG. MINIMUM)
Use the gauge to monitor manifold engine vacuum and
use the hand pump to check vacuum sensors, solenoids
and valves.
UNPOWERED TEST LIGHT
Used for checking wiring for a complete circuit, voltages
and grounds.
TACHOMETER
Must have inductive trigger signal pick-up.
➤
TACHOMETER
3
5
0
2
14
J 34142-B
J 39978
J 23738-A
SpecialTools (1 of 3)
01234567890
4000
mV
AUTO 100
ms RECORD MAX MIN AVG
AC DC
µm V A
n F S %
M k ΩHz
87 TRUE RMS MULTIMETER
400mA MAX
FUSED 10A MAX
FUSED
_
…
mV
V
V
Ω
~_
…
OFF
µA~
_
…~
_
…
A
mA
(
NS 14574

1 - 8 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
J 35689
J 28741-A/BT-8234-A
SpecialTools (2 of 3)
RT0086
J 34730-2C & J 34730-350/BT 8329
RTK0078
TA 06075
METRI-PACK TERMINAL REMOVER
Used for removing 150 series Metri-Pack “pull-to-seat”
terminals from connectors. Refer to wiring harness
service in MEFI General Information Section for removal
procedure.
WEATHER PACK TERMINAL REMOVER
UsedforremovingterminalsfromWeatherPackconnectors.
Referto wiring harnessservice in MEFI General Information
Section for removal procedure.
DIAGNOSTIC TROUBLE CODE (DTC) TOOL
A hand held diagnostic tool that plugs into the DLC
connector for various diagnostics.
FUEL PRESSURE GAUGE
Used for checking fuel system pressure on MFI and PFI
engines.
INJECTOR HARNESS TEST LIGHT
A specially designed light used to visually indicate injector
electrical pulses from the ECM.
DIACOM SCANTOOL
A hand held diagnostic tool that plugs into the DLC
connector for various diagnostics. It will display various
parameters.

5.0/5.7/6.0L/8.1L General Information 1 - 9
MEFI 4 - PCM
HARNESS TEST ADAPTER KIT
Usedto makeelectricaltest connectionsin currentWeather
Pack, Metri-Pack and Micro-Pack style terminals.
20’ DIAGNOSTIC CONNECTOR EXTENSION CABLE
Extension cable to go between the scan tool and the DLC
on the engine harness.
FUEL LINE QUICK-CONNECT SEPARATOR
Used to release fuel line quick-connect fittings.
INJECTOR TESTER
Separately energizes each injector to compare for equal
fuel pressure drops over a constant time interval.
TIMING LIGHT
Must have inductive signal pickup.
SpecialTools (3 of 3)
J 35616
TA 06076
J 39021
J 34186
4AMP MP
AMP
2.5 AMP
6.5 AMP
LOW BATTERY
READY TO TEST
TEST IN PROGRESS
INJECTOR
VOLTS
+
-
J-39021
PUSH TO TEST
KENT-MOORE
J 37088-A/BT-9171

1 - 10 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
BARO - BAROMETRIC PRESSURE
BAT - BATTERY, BATTERY POSITIVE
TERMINAL, BATTERY OR SYSTEM
VOLTAGE
B+ - BATTERY POSITIVE
CKP - CRANKSHAFT POSITION SENSOR
CKT - CIRCUIT
CMP - CAMSHAFT POSITION SENSOR
CONN - CONNECTOR
CYL - CYLINDER
DEG - DEGREES
DIAG - DIAGNOSTIC
DLC - DATA LINK CONNECTOR
DMM - DIGITAL MULTIMETER
DTC - DIAGNOSTIC TROUBLE CODE
ECM - ENGINE CONTROL MODULE
ECT - ENGINE COOLANT TEMPERATURE
SENSOR
EEPROM - ELECTRONIC ERASABLE
PROGRAMMABLE READ ONLY
MEMORY
EI - ELECTRONIC IGNITION
EMI - ELECTROMAGNETIC
INTERFERENCE
ENG - ENGINE
GND - GROUND
GPH - GALLONS PER HOUR
HVS - HIGH-VOLTAGE SWITCH
IAC - IDLE AIR CONTROL
IAT - INTAKE AIR TEMPERATURE
IC - IGNITION CONTROL
IGN - IGNITION
INJ - INJECTOR
I/O - INPUT/OUTPUT
kPa - KILOPASCAL
ABBREVIATIONS
KS - KNOCK SENSOR SYSTEM
KV - KILOVOLTS
MAP - MANIFOLD ABSOLUTE PRESSURE
MEFI - MARINE ELECTRONIC FUEL
INJECTION
MFI - MULTIPORT FUEL INJECTION
MIL - MALFUNCTION INDICATOR LAMP
MSEC - MILLSECOND
N/C - NORMALLY CLOSED
N/O - NORMALLY OPEN
OBD - ON-BOARD DIAGNOSTIC SYSTEM
CHECK
OPT - OPTIONAL
PFI - PORT FUEL INJECTION
PROM - PROGRAMMABLE READ ONLY
MEMORY
RAM - RANDOM ACESS MEMORY
REF HI - REFERENCE HIGH
REF LO - REFERENCE LOW
ROM - READ ONLY MEMORY
SLV - SLAVE
SW - SWITCH
TACH - TACHOMETER
TBI - THROTTLE BODY INJECTION
TERM - TERMINAL
TP - THROTTLE POSITION SENSOR
V - VOLTS
VAC - VACUUM
WOT - WIDE OPEN THROTTLE
“ HG - INCHES OF MERCURY

5.0/5.7/6.0L/8.1L General Information 1 - 11
MEFI 4 - PCM
OUTER JACKET
MYLAR
DRAIN WIRE
DRAIN WIRE
1REMOVE OUTER JACKET.
2UNWRAP ALUMINUM/MYLAR TAPE. DO NOT
 REMOVE MYLAR.
1LOCATE DAMAGED WIRE.
2REMOVE INSULATION AS REQUIRED.
3SPLICE TWO WIRES TOGETHER USING SPLICE
 CLIPS AND ROSIN CORE SOLDER.
3UNTWIST CONDUCTORS. STRIP INSULATION AS
 NECESSARY.
6TAPE OVER WHOLE BUNDLETO SECURE AS BEFORE.
4SPLICE WIRES USING SPLICE CLIPS AND ROSIN CORE
 SOLDER.WRAP EACH SPLICE TO INSULATE.
5WRAP WITH MYLAR AND DRAIN (UNINSULATED) WIRE.
4COVER SPLICE WITH TAPE TO INSULATE
 FROM OTHER WIRES.
5RETWIST AS BEFORE AND TAPE WITH
 ELECTRICALTAPE AND HOLD IN PLACE.
8-24-94
RS 22186
Figure 1-5 - Wiring Harness Repair
•Tendencyforconnectorsto come apartdue to vibration
and/or temperature cycling.
•Terminals not fully seated in the connector body.
•Inadequate terminal crimps to the wire.
On-Board Service
Wiring Harness Service
Figure 1-5
Wiring harnesses should be replaced with proper part
number harnesses.When wires are spliced into a harness,
use the same gauge wire with high temperature insulation
only.
With the low current and voltage levels found in the
system, it is important that the best possible bond be
made at all wire splices by soldering the splices as shown
in Figure 1-5.
Usecare whenprobing a connector or replacing a connector
terminal.It is possible to short between opposite terminals.
If this happens, certain components can be damaged.
Always use jumper wires with the corresponding mating
terminals between connectors for circuit checking. NEVER
probe through connector seals, wire insulation, secondary
ignition wires, boots, nipples or covers. Microscopic
damage or holes may result in water intrusion, corrosion
and/or component failure.
Diagnosis
The diagnostic tables and functional checks in this manual
aredesigned to locate a faulty circuit or componentthrough
logic based on the process of elimination. The tables are
prepared with the requirement that the system functioned
correctly at the time of assembly and that there are no
multiple failures.
Enginecontrol circuitscontain manyspecial design features
not found in standard vehicle wiring. Environmental
protection is used extensively to protect electrical contacts.
Proper splicing methods must be used when necessary.
The proper operation of low amperage input/output circuits
depend upon good continuity between circuit connectors.It
is important before component replacement and/or during
normal troubleshooting procedures that a visual inspection
of any questionable mating connector is performed.Mating
surfaces should be properly formed, clean and likely to
make proper contact. Some typical causes of connector
problems are listed below:
•Improperly formed contacts and/or connector
housing.
•Damaged contacts or housing due to improper
engagement.
•Corrosion, sealer or other contaminants on the contact
mating surfaces.
•Incomplete mating of the connector halves during
initial assembly or during subsequent troubleshooting
procedures.

1 - 12 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
RS 22187
Figure 1-6 - Metri-Pack Series 150 Terminal Removal
AB
1
4
5
322
1
1. METRI-PACK SERIES
150 FEMALE TERMINAL.
2. LOCKING TANG.
3. TOOL J35689 OR BT-8446.
4. CONNECTOR BODY.
5. SEAL.
Metri-Pack Series 150Terminals
Figure 1-6
Some ECM harness connectors contain terminals called
Metri-Pack (Figure 1-6). These are used at some of the
sensors and the distributor connector.
Metri-Pack terminals are also called “Pull-To-Seat”
terminals because,to installa terminalon a wire,the wireis
first inserted through the seal and connector.The terminal
is then crimped on the wire, and the terminal is pulled back
into the connector to seat it in place.
To remove a terminal:
1. Slide the seal back on the wire.
2. Insert tool J 35689 or equivalent, as shown in Figure
1-6, to release the terminal locking tang.
3. Push the wire and terminal out through the connector.
If the terminal is being reused, reshape the locking
tang.
Wiring Connector Service
Most connectors in the engine compartment are protected
against moisture and dirt which could create oxidation
and deposits on the terminals.This protection is important
because of the very low voltage and current levels found
in the electronic system. The connectors have a lock
which secures the male and female terminals together.
A secondary lock holds the seal and terminal into the
connector.
When diagnosing, open circuits are often difficult to locate
by sight because oxidation or terminal misalignment are
hidden by the connectors. Merely wiggling a connector on
a sensor, or in the wiring harness, may locate the open
circuit condition. This should always be considered when
an open circuit or failed sensors is indicated. Intermittent
problems may also be caused by oxidized or loose
connections.
Before making a connector repair, be certain of the type of
connector. Some connectors look similar but are serviced
differently.

5.0/5.7/6.0L/8.1L General Information 1 - 13
MEFI 4 - PCM
FEMALE
CONNECTOR
BODY
MALE
CONNECTOR
BODY
1. OPEN SECONDARY LOCK HINGE ON CONNECTOR
2. REMOVE TERMINAL USING TOOL
3. CUT WIRE IMMEDIATELY BEHIND CABLE SEAL
6. CLOSE SECONDARY LOCK HINGE
5. PUSH TERMINAL INTO CONNECTOR
UNTIL LOCKING TANGS ENGAGE
4. REPLACE TERMINAL
A. SLIP NEW SEAL ONTO WIRE
B. STRIP 5mm (.2") OF INSULATION FROM WIRE
C. CRIMP TERMINAL OVER WIREAND SEAL
TERMINAL REMOVAL TOOL
J 28742, J 38125-10 OR BT-8234-A
PUSH TO
RELEASE
WIRE
SEAL
SEAL
RS 22188
Figure 1-7 - Weather-Pack Terminal Repair
Weather-Pack Connectors
Figure 1-7
Figure 1-7 shows a Weather-Pack connector and the
tool (J28742 or equivalent) required to service it. This
tool is used to remove the pin and sleeve terminals. If
terminal removal is attempted without using the special
tool required, there is a good chance that the terminal
will be bent or deformed, and unlike standard blade type
terminals, these terminals cannot be straightened once
they are bent.
Make certain that the connectors are properly seated and
all of the sealing rings in place when connecting leads.
The hinge-type flap provides a secondary locking feature
for the connector. It improves the connector reliability by
retaining the terminals if the small terminal lock tangs are
not positioned properly.Weather-Pack connections cannot
be replaced with standard connections.

1 - 14 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
Important
•To ensure proper engine operation after repair of
connectorassembly, wires mustbe inproper connector
location. Before removing index cover, note if there
are any wires of the same color.Mark these wires from
the location that they were removed.For the remaining
wires, their location can be found by referring to“Wiring
Diagrams” in the Diagnosis section.The strain relief is
numbered for identifying wire location.
10. Index cover (4) by pushing in on Tabs C with a small
screwdriver.
11. Terminals by pulling out of connector.
12. Seal (2) from wires.
13. Strain relief (1) from wires.
Clean and Inspect
•Terminals for corrosion.
– Use spray electrical contact cleaner.
•Loose crimps on terminals.
•Broken wires at terminals.
Notice: For terminal replacement, refer to instructions
found with terminal repair kit and crimper tool.
Install or Connect
1. Align index cover (4) on connector (3) and lock into
position. Make sure Tabs C are locked.
2. Align seal (2) on connector (3) and slide all the way
on.
• DO NOT install strain relief (1) onto connector (3)
yet.
3. One wire with terminal installed, through strain relief
(1) in location that it was removed.
• Start with the lowest numbered wire position for
that connector.
4. Terminal through seal (2), connector (3) and into index
cover (4) until it locks in place.
5. Remaining wires one at a time per same method.
•Keep wires straight.
•DO NOT kink wires.
6. Strain relief (1) onto seal (2) and connector (3).
7. Lock Tabs B into strain relief (1).
8. Plugs into strain relief (1) where there are not any
wires.
9. Fold strain relief (1) together and lock Tabs A.
10. Connector assembly to ECM.
11. Negative battery cable.
Micro-Pack 100/W Series Connectors
Figure 1-8
The harness connectors used with the ECM “J1” and “J2”
connectors are Micro-Pack 100/W Series. It is used for its
ruggedized construction, capable of carrying more current
and provides good sealing ability. The connector is made
up of five different parts (refer to Figure 1-8View A):Strain
Relief (1), Seal (2), Connector (3), Index Cover (4) and
Terminals (not shown).
Remove or Disconnect
1. Negative battery cable.
2. Connector from ECM by lifting up locking tab with
thumb and pulling on connector body.
Inspect
•Check strain relief for being cracked or locking tab
damaged.
•Check index cover for being cracked.
•Check seal for being torn, twisted or out of shape from
improper installation.
•Check terminals for being corroded, out of position,
bent or stretched out.
– Use a wire gauge .038 for checking terminal
internal fit. Wire gauge should slide with smooth
feel and not be loose.
Notice: If you are only going to clean terminals, complete
disassembly is not necessary. Remove index cover from
the connector by pushing on Tab C on both sides and
sliding off cover.Care must be taken not to move terminals
out of their position. The index cover locks the terminals
in position. If repair or replacement of parts is needed, DO
NOT remove index cover at this time.
3. With a small screwdriver, move Tabs A on strain relief
(1) to unlock position.
4. Open strain relief as shown in View B.
5. Release Tabs B (View C) on connector (3) by pushing
inward with both thumbs or small screwdriver.
6. Push Tabs B through strain relief (1) with thumbs or
small screwdriver while in released position.
Important
•Where there are not wires in strain relief, small plugs
areinstalled.DONOTlose the plugs,theyare important
to help keep connector assembly sealed.
7. Remove plugs where there are not any wires.
8. Slide strain relief off of seal and back on wires.
9. Slide seal off of connector and back on wires.

5.0/5.7/6.0L/8.1L General Information 1 - 15
MEFI 4 - PCM
Figure 1-8 - Micro-Pack 100/W Series
21 3 4 5 6 7 8 9 10111213141516
1817 1920212223242526272829303132
12TAB B TAB C 34
TAB B TAB C
TAB A
TAB A
TAB A
TAB B
TAB B
FIGURE C - STRAIN RELIEF OPENED
FIGURE B - STRAIN RELIEF CLOSED
FIGURE A - EXPLODED VIEW OF CONNECTOR ASSEMBLY
1 STRAIN RELIEF
2 SEAL
3 CONNECTOR
4 INDEX COVER
PS 19745

1 - 16 General Information 5.0/5.7/6.0/8.1L
MEFI 4 - PCM
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