TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
DIAGNOSTIC AIDS:
Check for the following conditions;
•
Poor connections at ECM. Inspect harness connectors for backed out terminals,
improper mating, broken locks, improperly formed or damaged terminals, and poor
terminal to wire connections.
•
•
Damaged harness. Inspect the wiring harness for damage.
If the engine starts and stalls, it may set a false trouble code 41. Clear trouble codes and
repair stalling condition.
TEST DESCRIPTION:
Step 2. Trouble code 41 means the ECM has seen an open in the IC circuit. This test con-
firms trouble code 41 and that the fault causing the trouble code is present.
Step 3. Check for a normal IC ground path through the IC module.
Step 4. Confirms that trouble code 41 is a faulty ECM and not an intermittent open in CKT
423.
Code 41 (2 of 3): Ignition Control (IC) Circuit (Non-Scan) - Open IC Circuit
STEP
ACTION
VALUE
YES
NO
PROCEED TO
Go to
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
OBD
System
Check
1
2
–
Step 2
1.Install Marine Diagnostic Code Tool.
2.
Clear trouble code 41.
3.
Start engine and idle for 2 minutes or Ma-
rine Diagnostic Code Tool indicates a stored
trouble code.
4.
Ignition “ON,” engine “OFF.”
7.
Switch Marine Diagnostic Code Tool to
“Service Mode” and note trouble code.
Is trouble code 41 present?
1. Ignition “OFF.”
–
Step 3
Step 4
Step 8
Step 5
3
2.
Disconnect ECM harness connectors.
3000
6000
Ohms
to
3.
Using a DVOM set on OHMS, probe
ECM harness terminal J2-23 to ground.
Is resistance within specified value?
Page 5G-26
90-861326--1 MARCH 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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