Faulty Signal. Intermittent Fault

FAULTY SIGNAL. PERMANENT FAULT





Checking Ground Lead

- Ignition OFF.
- Wait for approx. 150 seconds (cars with immobilizer 245 seconds).
- Disconnect Knock Sensors (KS). Knock sensor (KS) connectors are located on the cable duct in front of the engine.
- Connect an ohmmeter between knock sensor (KS) connector terminal 2 (engine control module (ECM) side) and ground.

The ohmmeter should read approx. 0 Ohms.

If reading is OK:
- Proceed to Checking Signal Cable section below.

If reading is incorrect:
- Proceed to test step below.





Checking Engine Control Module Connector

- Ignition OFF.
- Knock sensor (KS) disconnected.
- Check engine control module (ECM) connector for contact resistance, oxidation and remedy.
- Engine control module (ECM) connected.
- Connect an ohmmeter between knock sensor (KS) connector terminal 2 and ground.

The ohmmeter should read approx. 0 Ohms.

If reading is OK:
- The diagnostic trouble code (DTC) has been caused by loose connections in the engine control module (ECM) connector.
- Then proceed to Verification section below.

If reading is incorrect:
- Check cable between knock sensor (KS) connector terminal 2 and engine control module (ECM) #A17 for an open-circuit.
- Then proceed to Verification section below.





Checking Signal Cable

- Ignition OFF.
- Knock sensor (KS) disconnected.
- Connect an ohmmeter between knock sensor (KS) connector terminal 3 and ground.

The ohmmeter should read approx. 1Meg Ohms.

If reading is OK:
- Proceed to Checking Knock Sensor Signal section below.

If value is lower:
- Check cable between knock sensor (KS) terminal 3 and engine control module (ECM) #A30 for a short-circuit to ground.
- Then proceed to Verification section below.

If value is higher:
- Proceed to test step below.





Checking Engine Control Module Connector

- Ignition OFF.
- Knock sensor (KS) disconnected.
- Check engine control module (ECM) connector for contact resistance, oxidation and remedy.
- Engine control module (ECM) connected.
- Connect an ohmmeter between knock sensor (KS) connector terminal 3 and ground.

The ohmmeter should read approx. 1Meg Ohms.

If reading is OK:
- The diagnostic trouble code (DTC) has been caused by loose connections in the engine control module (ECM) connector.
- Then proceed to Verification section below.

If reading is incorrect:
- Check cable between knock sensor (KS) terminal 3 and engine control module (ECM) #A30 for an open-circuit.
- Then proceed to Verification section below.





Checking Knock Sensor Signal

- Ignition OFF.
- Connect the knock sensor (KS).
- Start engine and run to normal operating temperature.
- Go into scrolling values list.
- Rev engine to 3,500 rpm.
- Read off the knock sensor (KS) signal value.

This value should be 2 - 6 at engine speeds above 3,500 rpm.

If reading is OK:
- The diagnostic trouble code (DTC) has been caused by loose connections in the knock sensor (KS) connector.
- Check connector for contact resistance, oxidation and remedy.
- Then proceed to Verification section below.

If reading is incorrect:
- Try a new knock sensor (KS).
- Then proceed to Verification section below.





Verification

Hint: After carrying out the repair, check that the fault has been remedied as follows.

- Ignition OFF.
- Reconnect connectors, reinstall components etc.
- START engine and RUN to normal operating temperature.
- Go into scrolling values list.
- Rev engine to 3,500 rpm.
- Read off the knock sensor (KS) value.

The value should be 2 - 6 at engine speeds above 3,000 rpm.

If reading is OK:
Fault corrected

If reading is incorrect:
- Proceed to test step below.

Fault-Tracing Information

- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?

Yes:
- Fault not corrected

No:
- Return to Checking Ground Lead section above.