EasyManuals Logo

Mercury MerCruiser MCM 7.4L MPI User Manual

Mercury MerCruiser MCM 7.4L MPI
1027 pages
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Page #732 background imageLoading...
Page #732 background image
SERVICE MANUAL NUMBER 23
TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
90-861326--1 MARCH 1999 Page 5F-35
Code 43 (2 of 3): Knock Sensor (KS) Circuit (Scan)
STEP ACTION VALUE YES NO
PROCEED TO
1
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
Step 2
Go to
OBD
System
Check
1. Install scan tool.
2 E i idli l t t t b
2
2. Engine idling, coolant temperature above
150°F
(
66° C
)
.
150 F
(66 C).
Does scan tool indicate a fixed value
greater than zero degrees of knock retard?
Step 3 Step 9
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
3. Start engine.
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?
Step 8 Step 4
1. Ignition OFF.
2. Disconnect ECM J-1 connector.
4
3. Ignition ON.
8-10
4
4. Connect a DVOM from ECM harness
connector terminal “J1-1” (CKT 485) to ground
(–).
810
Volts
Are 8-10 volts present?
Step 5 Step 7
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?
Step 14 Step 6
1. Disconnect knock module harness connec-
tor.
6
2. Connect a test light to battery positive (B+).
6
3. Touch the test light to KS harness connector
terminal “D” (CKT 486).
Is test light on?
Step 10 Step 13
Downloaded from https://needmanual.com/!
Index

Table of Contents

Questions and Answers:

Question and Answer IconNeed help?

Do you have a question about the Mercury MerCruiser MCM 7.4L MPI and is the answer not in the manual?

Mercury MerCruiser MCM 7.4L MPI Specifications

General IconGeneral
BrandMercury
ModelMerCruiser MCM 7.4L MPI
CategoryEngine
LanguageEnglish

Related product manuals