Mercury MerCruiser MCM 454 Mag MPI Service Manual page 635

GENERAL SYSTEM DIAGNOSTICS
MEFI 3 - J-1 Circuits (continued)
Circuit
(CKT)
Pin
Pin Num-
Func-
ber
tion
(#)
Knock
Sensor
Signal
J1-14 496
(Only
used on
7.4L MPI)
Injector
J1-17 468
Driver
ECM
J1-20 450
Ground
Fuel
Pump
J1-23 465
Relay
Driver
Ignition
J1-24 424
Control
Bypass
Audio
J1-26 29
Warning
Horn
IAC
J1-27 444
"B"
Low
IAC
J1-28 441
"A"
High
Knock
J1-30 496
Sensor
Signal
Serial
J1-32 461
Data
NOTE 1: Battery voltage for first two seconds, then 0 volts.
NOTE 2: Varies with temperature.
NOTE 3: Varies with manifold vacuum.
NOTE 4: Varies with throttle movement.
NOTE 5: Less than .5 volt (500 mV).
Index
Page 5E-42
Downloaded from https://needmanual.com/
Normal Voltage
Wire Wire
Color
Ignition Engine
ON Running
BLU – –
DK
B+ B+
GRN
0 0
BLK
(NOTE 5) (NOTE 5)
DK 0
B+
GRN/
(NOTE
WHT
1&5)
TAN/ 0
4.5V
BLK
(NOTE 5)
DK
– –
GRN
GRN/ Not Not
BLK Usable Usable
BLU/ Not Not
WHT Usable Usable
BLU – –
ORN 5V 5V
SERVICE MANUAL NUMBER 23
Diag-
nostic
Possible Possible
Trouble
Symptoms
Codes
DTC(s)
Poor Fuel Economy,
43, 44
Poor Performance
Detonation
None Rough Idle, Lack Of Power, Stall
Rough Running, Poor Idle, Lack
None
Of Performance
None
42 Lack Of Power, Fixed Timing
None
Rough Unstable or Incorrect
None
Rough Unstable or Incorrect
None
Poor Fuel Economy,
43, 44
Poor Performance
Detonation
No Serial Data
None
(NOTE 6)
90-861326--1 MARCH 1999
No Start
–
Idle
Idle