SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
Code 42 (3 of 3): Ignition Control (IC) Circuit (Scan)
1.
2.
3.
4.
Ignition OFF.
Disconnect ECM connectors.
Ignition ON.
Use a DVOM with selector in the OHMS
4
range.
5.
Probe ECM harness connector CKT 423
with DVOMto ground.
It should read more than 3000 Ohms.
Does it?
–
Step 5
Step 6
Probe ECM harness connector CKT 424 with a
test light to battery positive (B+).
5
6
Is test light on?
–
–
Step 14 Step 7
Open CKT 423, faulty connection or faulty igni-
tion module.
–
–
With Ohmmeter connected to ECM harness
CKT 423 and ground, probe harness CKT 424
with test light connected to battery positive
(B+).
7
8
As test light contacts CKT 424, resistance
should change from over 3000 Ohms to under
–
Step 9
Step 8
1000
Ohms.
Does it?
Disconnect distributor 4-way connector. Con-
nect ohmmeter between CKT 423 and ground.
Resistance should have gone high (open
circuit), does it?
–
–
–
Step 10 Step 11
Step 12 Step 13
Reconnect ECM and idle engine for 1 minute
or until code 42 sets.
9
CKT 424 open, faulty connections or faulty
ignition module.
10
–
–
11
12
CKT 423 shorted to ground.
Faulty ECM.
–
–
–
–
–
–
Code 42 is intermittent refer to “Diagnostic
Aids.”
13
14
–
–
–
Disconnect ignition module 4-way connector.
Is test light on?
–
–
–
Step 15 Step 16
15
16
CKT 424 shorted to ground.
Faulty ignition module.
–
–
–
–
Index
90-861326--1
MARCH 1999
Page 5F-33
| 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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