Knock Sensor (KS) , Checking
The following procedure is used to check Knock Sensor (KS) 1 G61 and Knock Sensor (KS) 2 G66.
Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.
- Cylinders 1, 2, and 3 (bank 1) are monitored by Knock sensor (KS) 1 -G61-. Cylinders 4, 5, and 6 (bank 2) are monitored by Knock sensor (KS) 2 -G66-.
- Knock sensors themselves cannot be checked electrically.
- When servicing terminals in the harness connector of knock sensors, use only gold-plated terminals.
- For the knock sensors to function properly, it is important that the tightening torque be exactly 20 Nm.
- Contact surfaces between Knock Sensor (KS) 1 G61 and Knock Sensor (KS) 2 G66 and cylinder block must be free of corrosion, dirt and grease.
Test requirements
- The mounting bolt of Knock Sensor (KS) 1 G61/Knock Sensor (KS) 2 G66 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 (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to → General Diagnosis .
Start diagnosis
- Remove the rear engine cover - arrows -.
Checking knock sensor and wiring
- The knock sensor electrical connectors can be identified by color. Knock Sensor (KS) 1 -G61- (Bank 1) is green. Knock Sensor (KS) 2 -G66- (Bank 2) is gray.
- Disconnect the electrical harness connector - 1 - or - 2 - of the respective knock sensor.
1 - Knock Sensor (KS) 1 -G61-.
2 - Knock sensor (KS) 2 -G66-.
Checking internal resistance
- Using a Multimeter , check the Knock Sensor terminals for an internal short.
| Knock Sensor (KS) Electrical harness connector terminals |
|---|
| 1 + 2 |
| 1 + 3 |
| 2 + 3 |
Specified value: ∞ (Infinity).
If the specified values are not obtained:
- Replace the faulty Knock Sensor (KS). Refer to → 15 - ENGINE - CYLINDER HEAD, VALVETRAIN .
If the specified values are obtained:
Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the test box. Refer to → 24 - FUEL INJECTION SYSTEM .
If the manufacturers test box is not being used. Perform the following step.
- Remove the Engine Control Module (ECM) J623. Refer to → Engine Control Module (ECM) J623 , Removing and Installing .
- 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.
| Knock Sensor (KS) 1 G61 electrical harness connector terminals | Engine Control Module (ECM) electrical harness connector T60 terminals or test box sockets |
|---|---|
| 1 | 41 |
| 2 | 58 |
| 3 | 42 |
| Knock Sensor (KS) 2 G66 electrical harness connector terminals | Engine Control Module (ECM) electrical harness connector T60 terminals or test box sockets |
|---|---|
| 1 | 56 |
| 2 | 57 |
| 3 | 42 |
Specified value: 1.5 Ω Max.
If the specified value was not obtained:
- Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
- Check the wiring connection for damage, corrosion, lose or broken terminals.
- If necessary, repair the faulty wiring connection.
If no malfunction is found in the wiring and the resistance was not OK:
- Replace the faulty Knock Sensor (KS). Refer to → 15 - ENGINE - CYLINDER HEAD, VALVETRAIN .
If no malfunction is found in the wiring and the resistance was OK:
- Replace the Engine Control Module (ECM) J623. Refer to → Engine Control Module (ECM) J623 , Removing and Installing .
Assembly is performed in the reverse order of removal, note the following:
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
- Check the DTC memory.
- If necessary, erase the DTC memory. Refer to Diagnostic Mode 04: Reset/delete Diagnostic Data .
- If the DTC memory was erased, generate readiness code. Refer to Readiness Code .
- End diagnosis and switch ignition off.