Mercury MerCruiser MCM 7.4L MPI User Manual

TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
90-861326--1 MARCH 1999 Page 5G-59
Code 41 (2 of 3): Ignition Control (IC) Circuit (Scan) Open IC Circuit
DIAGNOSTIC AIDS:
Check for the following conditions:
• Poor connection at ECM. Inspect harness connectors for backed out terminals,
improper mating, broken locks, improperly formed or damaged terminals and poor ter-
minal to wire connection.
• Damaged harness. Inspect the wiring harness for damage.
• If the engine starts and stalls, it may set a false DTC 41 or 42. Clear DTC’s and repair
stalling condition.
After repairs, clear DTC’s following “Clearing Trouble Codes” procedure at the front of this
section. Failure to do so may result in DTC’s not properly being cleared.
TEST DESCRIPTION:
Step 2. DTC 41 means the ECM has seen an open in the IC circuit. This test confirms
DTC 41 and that the fault causing the DTC is present.
Step 3. Checks for a normal IC ground path through the Ignition Control (IC) module.
Step 4. Confirms that DTC 41 is a faulty ECM and not an intermittent open in CKT 423.
STEP
ACTION VALUE YES NO
PROCEED TO
1
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
– Step 2
Go to
OBD
System
Check
2 1. Clear trouble code 41.
2. Start engine and idle for 2 minutes or
until trouble code 41 sets.
Is trouble code 41 present? – Step 3 Step 8
3 1. Ignition “OFF”.
2. Disconnect ECM harness connectors.
3000 to
3. Using a DVOM selected for Ohms, probe
ECM harness terminal J2-23 to ground.
6000
Ohms
Is resistance within the specified value? Step 4 Step 5
4 1. Reconnect ECM.
2. Start engine and idle for 2 minutes or
trouble code 41 sets.
Is trouble code 41 present? – Step 7 Step 8
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Index

Mercury MerCruiser MCM 7.4L MPI Specifications

General

Brand	Mercury
Model	MerCruiser MCM 7.4L MPI
Category	Engine
Language	English