Knock Sensor 1 - G61-, Checking

General Description

The Knock Sensor 1 -G61- is a tuned accelerometer on the engine which converts engine vibration to an electrical signal. The Engine/Motor Control Module -J623- uses this signal to determine the presence of engine knock and to retard spark timing, if necessary.

Special tools and workshop equipment required

Multimeter.
Wiring Diagram.
Scan Tool.

Test requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

NOTE:

Prior to beginning the test procedure, make sure to check the items listed below:

Poor fuel quality

Ignition timing malfunction

Loose components on the engine block

Engine temperature must be in the normal range

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2. -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. CONNECT: Scan tool. START: Engine and let Idle. CHECK: The ignition advance timing value. TAP: Near the Knock Sensor 1 -G61- area and monitor for any fluctuations in the ignition timing advance value. IGNITION: OFF. SPECIFIED VALUE: 1 - 10 degrees of ignition timing fluctuation. -- Was Value obtained?	-- YES: CONDITION: May be intermittent. PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 4. -- NO: GO TO: Step 3.
3	REMOVE: Engine/Motor Control Module - J623-. Refer to appropriate Service Information. DISCONNECT: Knock Sensor 1 -G61- harness connector. CHECK: Knock Sensor 1 -G61- harness connector terminal 1 to the Engine/Motor Control Module - J623- harness connector T56b / 29 for resistance. CHECK: Knock Sensor 1 -G61- harness connector terminal 2 to the Engine/Motor Control Module - J623- harness connector T56b / 30 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: TIP: The Knock Sensor 1 -G61- may fail under loaded operation; please swap a known good Knock Sensor 1 -G61- prior to continuing to the next step. GO TO: Step 4. -- NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 4.
4	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine/Motor Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine/Motor Control Module -J623-. Refer to appropriate Service Information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return, the repair is complete. Return vehicle to customer.