Mercury MerCruiser MCM 502 Mag MPI

GENERAL SYSTEM DIAGNOSTICS SERVICE MANUAL NUMBER 23
Page 5E-26 90-861326--1 MARCH 1999
MEFI 2 - 7.4L MPI Symptom Chart (J-1 Circuits)
Pin
Circuit
(CKT)
Wire
Normal Voltage
Diagnostic
Tro ble
Possible
Pin
Pin
Function
(CKT)
Number
(#)
Wire
Color
Ignition
ON
Engine
Running
Tro
u
ble
Codes
DTC(s)
Possible
Symptoms
J1-1
Knock
Sensor
Signal
485 GRN 9.5V 9.5V 43
Poor Fuel
Economy,
Poor Perfor-
mance Deto-
nation
J1-2
ECT
Signal
410 YEL
1.95V
(NOTE 2)
1.95V
(NOTE 2)
14
Poor Perfor-
mance, Ex-
haust Odor,
Rough Idle
RPM Reduc-
tion
J1-3 Not Used – – – – – –
J1-4
Discrete
Switches
911 BRN – – None
Audio Warn-
ing Activated
(Low Oil
Pressure/
Low I/O
Fluid/Trans-
mission
Fluid/Over-
heat) Note:
Earlier Mod-
els Use J1-4
J1-5
Master/
Slave
916 YEL B+ B+ None
Lack Of
Data From
Other En-
gine (Dual
Engine
Only)
J1-6
Discrete
Switches
911 BRN – – None
Audio Warn-
ing Activated
(Low Oil
Pressure/
Low I/O
Fluid/Trans-
mission
Fluid/Over-
heat) Note:
Later Mod-
els Use J1-6
J1-7
Diagnos-
tic Test
451
BLK/
WHT
B+ B+ None
Incorrect
Idle, Poor
Performance
J1-8 Not Used – – – – – –
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