Mercury 305 CID - Page 638

ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY) - 5E-9790-823225--1 1096
Code 43: Knock Sensor (KS) Circuit (Non-Scan)
(2 of 2)
• DISCONNECT 5 WAY KS MODULE CONNECTOR.
• USING DVM, MEASURE RESISTANCE BETWEEN
TERMINAL “E” AND GROUND.
• RESISTANCE SHOULD BE BETWEEN 3.3KΩ AND 4.5KΩ
OHMS.
IS IT?
1
3
NOYES
• IGNITION “OFF.”
• DISCONNECT ECM CONNECTOR J-2
• IGNITION “ON.”
• CONNECT DVOM FROM ECM HARNESS
CONNECTOR TERMINAL “C” (CKT 485) TO
GROUND.
ARE 8-10 VOLTS PRESENT?
INSPECT KNOCK SENSOR TERMINAL
CONTACTS. IF OK, REPLACE KNOCK
SENSOR.
NO YES
FAULTY ECM.
2
CHECK FOR OPEN OR SHORT
IN CKT 496.
IF OK, REPLACE KNOCK
SENSOR.
• RECONNECT 5 WAY KS MODULE CONNECTOR.
• DISCONNECT KNOCK SENSOR HARNESS CONNECTOR.
• CONNECT A TEST LIGHT TO BATTERY POSITIVE BATTERY POSITIVE (B+).
• START ENGINE.
• HOLD ENGINE SPEED STEADY AT 2500 RPM.
• 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?
NO YES
• DISCONNECT KS MODULE HARNESS
CONNECTOR.
• CONNECT A TEST LIGHT TO BATTERY
POSITIVE B+.
• TOUCH THE TEST LIGHT TO KS HARNESS
CONNECTOR TERMINAL “D” (CKT 486).
IS THE TEST LIGHT “ON”?
YES NO
CKT 485 OPEN
OR
SHORTED TO GROUND
OR
FAULTY KS MODULE.
REPAIR OPEN
OR
GROUNDED
CKT 439.
NOYES
• ALLOW DVM VOLTAGE TO STABILIZE.
• TOUCH A TEST LIGHT CONNECTED TO
B+ TO THE KNOCK SENSOR HARNESS
CONNECTOR TERMINAL (CKT 496).
DOES THE VOLTAGE VALUE CHANGE?
• CONNECT A TEST LIGHT TO GROUND.
• DISCONNECT KS MODULE HARNESS CONNECTOR.
• TOUCH THE TEST LIGHT TO KS MODULE HARNESS
CONNECTOR TERMINAL “B” (CKT 439).
IS THE TEST LIGHT “ON”?
YES NO
CKT 496 OPEN
OR
SHORTED TO GROUND
OR
FAULTY KS MODULE.
REPAIR OPEN
GROUND CKT
486.
4
5
6