5.0/5.7/6.0/8.1L Diagnosis 5 - 1
MEFI 4 - PCM
Marine Electronic Fuel Injection (MEFI 4/4B)
Section 5
Diagnosis
This section will be used to perform diagnostic procedures on the Marine Electronic Fuel Injection (MEFI 4/4B) equipped
engines. It describes the system circuits and diagnostic procedures used to diagnose the circuits. It will be used to correct
Diagnostic Trouble Codes (DTCs) by following step-by-step procedures. This section contains the On-Board Diagnostic
(OBD) System Check, which MUST be the fi rst step performed, before any other diagnostics or repairs are made to the
MEFI 4/4B system.
The assumption is made that on all diagnostic procedures, the engine is equipped with MEFI 4/4B ECM, sensors, wiring
harness, fuel components and ignition components. The wiring schematics and circuit identifi cations are for the MEFI
4/4B originally equipped wiring harness.
The Diagnostic Procedures (DP) and voltages shown are prepared with the requirement that the system functioned correctly
at the time of assembly and that there are no multiple failures.
Contents
DTC 41 EST Fault - EST A Fault. (5.0/5.7L Ignition
Control Circuit) ........................................Page 98
DTC 41
EST Fault - EST A Fault. (Cylinder/Coil #1)
(6.0/8.1L) ...................................................Page 100
DTC 41
EST Fault - EST D Fault. (Cylinder/Coil #2)
(6.0/8.1L) ...................................................Page 102
DTC 41
EST Fault - EST H Fault. (Cylinder/Coil #3)
(6.0/8.1L) ...................................................Page 104
DTC 41
EST Fault - EST G Fault. (Cylinder/Coil #4)
(6.0/8.1L) ...................................................Page 106
DTC 41
EST Fault - EST F Fault. (Cylinder/Coil #5)
(6.0/8.1L) ...................................................Page 108
DTC 41
EST Fault - EST E Fault. (Cylinder/Coil #6)
(6.0/8.1L) ...................................................Page 110
DTC 41
EST Fault - EST C Fault. (Cylinder/Coil #7)
(6.0/8.1L) ...................................................Page 112
DTC 41
EST Fault - EST B Fault. (Cylinder/Coil #8)
(6.0/8.1L) ...................................................Page 114
DTC 44 Knock Sensor 1 Circuit Scan ................ Page 116
DTC 44 Knock Sensor 2 Circuit Scan ................ Page 118
DTC 51 Calibration Checksum Failure Scan .....Page 120
DTC 81 Exhaust Temperature Switch Fault .......Page 122
DTC 81 Crankshaft Position Sensor Fault .........Page 124
DTC 81 Camshaft Position Sensor Fault ...........Page 128
DTC 81 Depspower Out of Range .....................Page 132
DTC 81 5 Volt Reference Out of Range ...........Page 134
DTC 81 Fuel Pump Relay Driver Circuit ............Page 136
DTC 81 Fuel Injector A Circuit ............................Page 140
DTC 81 Fuel Injector B Circuit ...........................Page 144
PCM Master Engine Specifi cations ....................Page 147
Diagnosis ................................................................ Page 2
Specifi cations .........................................................Page 3
Typical Scan Tool Data Values ...............................Page 5
Engine Scan Tool Data Defi nitions .........................Page 8
ECM Diagnostic Trouble Codes ...........................Page 10
Logged Warnings ............................................Page 11-12
Clearing Diagnostic Trouble Codes ......................Page 12
Fuel System Specifi cations ..................................Page 13
Engine Controls Wiring Schematics (6.0/8.1L) ....Page 14
Engine Controls Wiring Schematics (5.0/5.7L)
...... Page 28
ECM Connector Pinout Identifi cation (5.0/5.7L)
......Page 36
ECM Connector Pinout Identifi cation (6.0/8.1L)
.....Page 38
Connector Pinout Identifi cation (6.0/8.1L)
.............. Page 40
OBD System Check Scan
.....................................Page 46
DP A-1 No Malfunction Indicator Lamp
.................. Page 50
DP A-2 MIL On Steady - Will Not Flash DTC 12
.....Page 54
DP A-3 Engine Cranks But Will Not Run .............Page 56
DP A-4 Fuel System Diagnosis ............................Page 60
DP A-5 Fuel Pump Relay Circuit Diagnosis .........Page 66
DP A-6 System Relay Diagnosis ..........................Page 70
DP-7A Distributor Ignition Diagnosis (5.0/5.7L)
.....Page 72
DP-7B Electronic Ignition Diagnosis (6.0/8.1L) ...Page 78
DP-8 IAC Functional Test .....................................Page 80
DTC 14 ECT Sensor Circuit Low Scan ................Page 82
DTC 15 ECT Sensor Circuit High Scan ...............Page 84
DTC 21 TP Sensor Circuit High Scan ..................Page 86
DTC 22 TP Sensor Circuit Low Scan ...................Page 88
DTC 23 IAT Sensor Circuit Low Scan ..................Page 90
DTC 25 IAT Sensor Circuit High Scan .................Page 92
DTC 33 MAP Sensor Circuit High Scan ...............Page 94
DTC 34 MAP Sensor Circuit Low Scan ...............Page 96
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