Mercury MerCruiser MCM 454 Mag MPI Service Manual page 634

SERVICE MANUAL NUMBER 23
MEFI 3 - ECM J-1 and J-2 Circuit/Symptom Chart
In the following J-1 and J-2 Circuit/Symptom Charts only those pins which are used by the
ECM are shown. Pin numbers not listed are not used.
The "B+" Symbol indicates a system voltage (battery).
IMPORTANT: The following conditions must be met before testing.
1. Engine at operating temperature.
2. Ignition on or engine running.
3. Scan tool not connected.
J-1 Circuits
Pin
Pin
Func-
tion
Injector
J1-1
Driver
Ignition
Control
J1-3
Ref.
Low
ECM
J1-4
Ground
ECM
J1-5
Ground
MIL
J1-9
Lamp
Ignition
J1-10
Control
Signal
IAC "B"
J1-11
Low
IAC "A"
J1-12
Low
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
90-861326--1 MARCH 1999
Downloaded from https://needmanual.com/
Circuit
Normal Voltage
(CKT)
Wire Wire
Num-
Color
Ignition
ber
ON
(#)
DK
467 B+
BLU
RED/ 0
453
BLK
(NOTE 5)
0
450 BLK
(NOTE 5)
0
450 BLK
(NOTE 5)
BRN/ 0
419
WHT
(NOTE 5)
0
423 WHT
(NOTE 5)
GRN/ Not
443
WHT Usable
BLU/ Not
442
BLK Usable
Diag-
nostic
Trouble
Engine
Codes
Running
DTC(s)
B+ None
0
None
(NOTE 5)
0
None
(NOTE 5)
0
None
(NOTE 5)
0
None
(NOTE 5)
1.2V 42
Not
None Rough Unstable or Incorrect Idle
Usable
Not
None Rough Unstable or Incorrect Idle
Usable
GENERAL SYSTEM DIAGNOSTICS
Possible Possible
Symptoms
Rough Idle, Lack Of Power,
Stalling
Poor Performance
No Start
No Start
Lamp Inoperative
Stall, Will Restart In Bypass
Mode, Lack Of Power
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