Mercury MerCruiser MCM 454 Mag MPI Service Manual page 716

SERVICE MANUAL NUMBER 23
Code 43 (3 of 3): Knock Sensor (KS) Circuit (Non-Scan)
Index
90-861326--1 MARCH 1999
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STEP
1. Disconnect knock module harness con-
nector.
2. Connect a test light to battery positive
(B+).
6
3. Touch the test light to KS harness con-
nection terminal "D" (CKT 486).
Is test light on?
1. Connect a test light to ground.
2. Disconnect KS module harness connec-
tor.
7 7
3. Touch the test light to KS module har-
ness connector terminal "B" (CKT439).
Is the test light on?
Inspect knock sensor terminal contacts. If OK,
8
replace knock sensor.
Check for open or short in CKT 496. If OK,
9
replace knock sensor.
CKT 496 open, shorted to ground, or faulty
10
knock sensor module.
CKT 485 open, shorted to ground, or faulty
11
knock sensor module.
12 Repair open or grounded CKT 439.
13 Repair open ground CKT 486.
14 Faulty ECM.
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
ACTION VALUE YES NO
PROCEED TO
– Step 10 Step 13
– Step 11 Step 12
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