DIAGNOSTICS
SERVICE MANUAL NUMBER 24
Chart A-2 (1 of 2): MIL ON Steady - Will Not Flash DTC 12
ECM
MEFI 1
MEFI 3
MEFI 2
J1-18
J1-14
461
ORN/BLK or ORN
J1-32
J1-4
J1-5
450
BLK/WHT or BLK
BLK/WHT or BLK
450 BLK/WHT or BLK
TO ECM 15A
BATTERY
450
DLC
FUSE
CONNECTOR
J1-30
J1-7
J1-20
TO ECM 15A
BATTERY
FUSE
450
BLK/WHT or BLK
J2-22
451
WHT/BLK
(BLK/WHT - Some Models)
J2-31
J1-11
J1-9
IGN, INJECTOR KS
MODULE 10 AMP
FUSE
J2-32
439
PNK/BLK or PNK
J1-32
J1-16
J2-1
CIRCUIT DESCRIPTION:
When the CodeMate Tester is installed, it plugs into the DLC terminals “F” and “E.” It
receives voltage throughCKT 440 terminal “F.” Terminal “E” is ground through CKT 419 from
the ECM. There should always be a steady MIL with the ignition ON and the engine stopped.
The Engine Control Module (ECM) turns the MIL ON by grounding the MIL driver circuit.
When the diagnostic tests terminal on the DLC is grounded by jumping terminal “B” to termi-
nal “A,” the ground circuit is completed. The MIL will flash a DTC 12 followed by any DTC
stored in memory. A steady light suggests CKT 419 is shorted to ground or an open in CKT
451
from the ECM to the DLC.
DIAGNOSTIC AIDS:
An intermittent may be caused by a poor connection, rubbed through wire insulation or a
wire broken inside the insulation. Check for the following items:
•
Poor connection or damaged harness. Inspect the ECM harness and connectors for
improper mating, broken locks, improperly formed or damaged terminals, poor termi-
nal to wire connection and damaged harness.
If the engine runs OK, check for a faulty light bulb or an open in the MIL driver circuit (CKT
If the engine cranks but will not run, check for an open ECM ignition or battery feed
or a poor ECM to engine ground.
419).
Index
Page 5G-28
90-861327--1 OCTOBER 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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