Knock Sensor, Checking

The following procedure is used to diagnose all Knock Sensors --.

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The mounting bolt of Knock Sensor (KS) 1 -G61- tightened to 20 Nm.
• The Engine Control Module (ECM) - J623- fuses OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground connections between engine/transmission/chassis OK.
• Ignition switched Off.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis 

-- Disconnect the green Knock Sensor (KS) 1 -G61- electrical harness connector.

Checking internal resistance 

-- Using a multimeter, check the Knock Sensor terminals 1 to 2 for an internal short.

Specified value: 4.84 M Ω (+/- 1 M Ω).

If the specified value was Not obtained: 

-- Replace the faulty Knock Sensor (KS) 1 -G61-.

If the specified value was obtained: 

Checking wiring 

-- Remove the Engine Control Module (ECM) -J623-.

-- Using a multimeter, Check the Knock Sensor electrical harness connector to the Engine Control Module (ECM)J623 electrical harness connector T60 for an open circuit. Refer to wiring diagrams.

Knock Sensor (KS) 1 -G61- electrical harness connector terminals:	Engine Control Module -J623- electrical harness connector T60 terminals:
1	8
2	9
Shielding wire	40

Specified value: 1.5 Ω Max.

If the specified value was Not obtained: 

-- Check the wiring connection for an open circuit, high resistance or short circuit to Battery (+) or Ground.

-- Check the wiring connection for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained: 

If no malfunction is found in the wiring and the sensor resistance was OK: 

-- Replace the Engine Control Module (ECM) -J623-.

Final procedures 

After the repair work, the following work steps must be performed in the following sequence: 

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .