Mercury MerCruiser MCM 454 Mag MPI Service Manual page 485

MULTI-PORT FUEL INJECTION DESCRIPTIONS AND SYSTEM OPERATION
The ECM controls the primary current going to the ignition coil. It sends a voltage signal to
the IC module that sends a voltage signal to the ignition coil. This signal will trigger the coil
creating secondary spark to be produced. The secondary spark is sent to the distributor and
then to the correct cylinder by high tension leads.
The Ignition Control (IC) module maintains the base ignition timing. It also has a 27-degree
spark advance built into it in case there is a Code for an IC operation failure detected while
the engine is running. The engine will continue to run but at reduced performance.
BLK = BLACK
BLU = BLUE
BRN = BROWN
GRY = GRAY
GRN = GREEN
ORN = ORANGE
PNK = PINK
PUR = PURPLE
RED = RED
TAN = TAN
WHT = WHITE
YEL = YELLOW
LIT = LIGHT
DRK = DARK
k
Typical System Shown
m -
Index
Page 5B-26
Downloaded from https://needmanual.com/
m
A B
BRN
PNK
l
B A
902
B
RED
j
a - ECM Ground
b - ECM Ground
c - ECM Ground
d - Ignition Control
e - Distributor Reference HIGH
f - Bypass
g - Distributor Reference LOW
h - To Tachometer
i - 2-Way Black Connector
j - 2-Way Gray Connector
k - From Ignition Relay
l - 2-Way Coil Jumper Harness
IC Module
n - 8 Cylinder Distributor
o - Pick-up Coil
n
o
430 PUR/WHT
424 TAN/BLK
453 RED/BLK
i
121 WHT
A h
SERVICE MANUAL NUMBER 23
ECM
a
450 BLK
J1-4
b
450 BLK J1-5
c
450 BLK J1-20
d
J1-10
423 WHT
e
J2-10
f
J1-24
g
J1-3
90-861326--1 MARCH 1999
76082