Mercury MerCruiser MIE 7.4L MPI - Page 716

SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
90-861326--1 MARCH 1999 Page 5F-19
Code 43 (3 of 3): Knock Sensor (KS) Circuit (Non-Scan)
STEP ACTION VALUE YES NO
PROCEED TO
1. Disconnect knock module harness con-
nector.
6
2. Connect a test light to battery positive
(B+).
3. Touch the test light to KS harness con-
nection terminal “D” (CKT 486).
Is test light on? – Step 10 Step 13
1. Connect a test light to ground.
7
2. Disconnect KS module harness connec-
tor.
7
3. Touch the test light to KS module har-
ness connector terminal “B” (CKT439).
Is the test light on? – Step 11 Step 12
8
Inspect knock sensor terminal contacts. If OK,
replace knock sensor.
– – –
9
Check for open or short in CKT 496. If OK,
replace knock sensor.
– – –
10
CKT 496 open, shorted to ground, or faulty
knock sensor module.
– – –
11
CKT 485 open, shorted to ground, or faulty
knock sensor module.
– – –
12 Repair open or grounded CKT 439. – – –
13 Repair open ground CKT 486. – – –
14 Faulty ECM. – – –
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Index