DTC 1-4-3

1-4-3 KNOCK SENSOR SIGNAL, FRONT

Condition(s) for DTCs
^ The DTC is recorded if the engine speed is at least 2970 rpm and a certain engine load is exceeded, or if the signal from either Knock Sensor (KS) to the ICM is less than 225 mV for 96 successive ignitions.

Substitute value
^ The ICM retards the timing to eliminate knock.

Fault source(s)
^ Open-circuit in signal or ground lead.
^ Signal lead short-circuited to ground.
^ Faulty sensor.

Fault symptom(s)
^ Impaired performance may result.

TESTING PROCEDURE





Status message
^ Check current Status Message.

If Status message is: Permanent fault, signal faulty:
- Proceed to: PERMANENT FAULT, SIGNAL FAULTY Section below.
If Status message is: Intermittent fault, signal faulty:
- Proceed to: INTERMITTENT FAULT, SIGNAL FAULTY Section below.

^ The fault counter indicates the number of starts during which control module has detected a fault free signal after the DTC has been recorded.

PERMANENT FAULT, SIGNAL FAULTY

Disconnection of sensors
^ The following steps are required to gain access to the Knock Sensor connectors:

Front Knock Sensor:
^ Remove engine cooling fan and intake manifold support bracket.
^ Reinstall components on completion of fault tracing.

Rear Knock Sensor:
^ Turn ignition and radio OFF.
^ Disconnect battery ground lead.
^ Remove starter motor terminal shield.
^ Remove engine cooling fan.
^ Remove sensor connector with suitable tool, such as long screwdriver.
^ Reconnect battery ground lead.
^ Reinstall components on completion of fault tracing.
^ Continue with checking of ground lead.





Checking ground lead
^ Switch OFF ignition.
^ Disconnect sensor.
^ Connect ohmmeter between sensor connector terminal 2 and ground.

Instrument should indicate approx. 0 Ohms.

If reading is correct:
- Check signal lead.
If reading is incorrect:
- Check lead between ICM A23 (DTC 1-4-3) or ICM A24 (DTC 4-3-3) and connector terminal 2 for open-circuit.





Checking signal lead
^ Switch OFF ignition.
^ Disconnect sensor.
^ Connect ohmmeter between sensor connector terminal 2 and ground.

Instrument should indicate approx. 1Meg Ohms.

If reading is correct:
- Check sensor signal.
If resistance is infinite (no conductivity):
- Check lead between ICM A22 (DTC 1-4-3) or ICM A25 (DTC 4-3-3) and connector terminal 1 for open-circuit.
If Instrument indicates approx. 0 Ohms:
- Check lead between ICM A22 (DTC 1-4-3) or ICM A25 (DTC 4-3-3) and connector terminal 1 for short-circuit to ground.





Checking sensor signal
^ Connect KS (if disconnected).
^ Display DTC parameter list.
^ START engine and allow to idle at min. 3500 rpm.
^ Read value of sensor signal in DTC parameter list.

KNOCK 1 = Front KS
KNOCK 2 = Rear KS

Value should be 2 - 7 at speeds above 3500 rpm.

If reading is correct:
- DTC is due to poor connection in sensor connector.
- Check connector for contact resistance and oxidation.
If reading is incorrect:
- Try with new sensor.

INTERMITTENT FAULT, SIGNAL FAULTY





Checking wiring and connections
^ Check sensor and ICM connectors for loose connections, and for contact resistance and oxidation.
^ Check lead between ICM A22 (DTC 1-4-3) or ICM A25 (DTC 4-3-3) and connector terminal 1 for intermittent short-circuit to ground and for intermittent open-circuit.
^ Check lead between ICM A23 (DTC 1-4-3) or ICM A24 (DTC 4-3-3) and connector terminal 2 for intermittent open-circuit.