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- /Knock Sensor (KS) 2 -G66- tightened to 20 Nm.
- The Motronic Engine Control Module (ECM) - J220- 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
-- Remove the engine cover. Refer to the Repair information.
Before disconnecting the Knock Sensor electrical harness connectors, mark the connectors if the same color connectors are used.
-- Disconnect the Knock Sensor (KS) 1 -G61- electrical harness connector or the Knock Sensor (KS) 2 -G66- electrical harness connector.
Checking internal resistance
Correct ohm meter polarity MUST be followed or the results will be in error,
-- Using a multimeter, check the Knock Sensor terminals 1 to 2 for resistance.
Specified value: near 4.85 M Ω
-- Using a multimeter, check the Knock Sensor terminals 1 to 3 for resistance.
Specified value: OL or no continuity
If any of the specified values were Not obtained:
-- Replace the faulty Knock Sensor (KS) 1 -G61- /Knock Sensor (KS) 2 -G66-.
If the specified values were obtained:
Checking wiring
If the manufacturers test box is being used, perform the following step.
-- Install the test box.
If the manufacturers test box is not being used, perform the following step.
-- Remove the Motronic Engine Control Module (ECM) -J220-. Refer to the Repair information.
-- Using a multimeter, Check the Knock Sensor electrical harness connector to the Motronic Engine Control Module (ECM)J220 electrical harness connector T121 for an open circuit.
| Knock Sensor (KS) 1 -G61- electrical harness connector terminals | Motronic Engine Control Module (ECM) electrical harness connector T121 terminals or test box sockets |
|---|---|
| 1 | 106 |
| 2 | 99 |
| 3 | 108 |
| Knock Sensor (KS) 2 -G66- electrical harness connector terminals | Motronic Engine Control Module (ECM) electrical harness connector T121 terminals or test box sockets |
|---|---|
| 1 | 107 |
| 2 | 99 |
| 3 | 108 |
Specified value: 1.5 Ω Max.
If the specified value was Not obtained:
-- Check the wiring connection for an open circuit, high resistance, 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 no malfunction is found in the wiring and the resistance was OK:
-- Replace the Motronic Engine Control Module (ECM) -J220-. Refer to the Repair information.
-- Install the engine cover with air filter. Refer to the Repair information.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .