Mercury MerCruiser MCM 454 Mag MPI Service Manual page 732

SERVICE MANUAL NUMBER 23
Code 43 (2 of 3): Knock Sensor (KS) Circuit (Scan)
Index
90-861326--1 MARCH 1999
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STEP
Was the "On-Board Diagnostic" (OBD) System
1
Check Performed?
1. Install scan tool.
2 E 2. Engine idling, coolant temperature above i idli
2
150 F (66 C). 150 F (66 C).
Does scan tool indicate a fixed value
greater than zero degrees of knock retard?
1. Reconnect 5-way KS module connector Dis-
connect knock sensor harness connector.
2. Connector a test light to battery positive bat-
tery positive (B+).
3. Start engine.
3 3
4. Hold engine speed steady at 2500 rpm.
5. Repeatedly touch test light to knock sensor
harness connector terminal (CKT 496).
Does a noticeable rpm drop occur or using
timing light, did timing drop?
1. Ignition OFF.
2. Disconnect ECM J-1 connector.
3. Ignition ON.
4 4
4. Connect a DVOM from ECM harness
connector terminal "J1-1" (CKT 485) to ground
(–).
Are 8-10 volts present?
1. Allow DVOM voltage to stabilize.
2. Connect a test light to battery positive (B+).
5
3. Touch test light to knock sensor connector
terminal (CKT 496).
Does voltage value change?
1. Disconnect knock module harness connec-
tor.
2. Connect a test light to battery positive (B+).
6 6
3. Touch the test light to KS harness connector
terminal "D" (CKT 486).
Is test light on?
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
ACTION
l t t t b
VALUE YES NO
PROCEED TO
Go to
OBD
– Step 2
System
Check
–
Step 3 Step 9
– Step 8 Step 4
8-10 8 10
Volts
Step 5 Step 7
– Step 14 Step 6
– Step 10 Step 13
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