DTC 4-3-3

4-3-3 REAR KNOCK SENSOR SIGNAL




Trouble Code Conditions
If the signal from the Knock Sensor (KS) is less than 255 mV when engine speed exceeds 3000 rpm, load exceeds 3.0 ms and this continues for 96 ignitions in succession, a Diagnostic Trouble Code (DTC) is set for the knock sensor.

Substitute value(s)
- Ignition advance reduced for safety.
- Injected fuel quantity increased to cool mixture.

Fault source(s)
- Faulty camshaft adjustment.
- Signal lead short circuit to ground.
- Break in signal lead.
- Break in ground lead.
- Contact resistance in connections.
- Defective knock sensor.

Fault symptom(s)
- Poor performance due to reduced ignition advance.

TEST PROCEDURE




OTHER DTC's
- Read out other DTCs.

If DTC 1-2-3, 3-1-4, 4-1-3 and/or 4-1-1 (2-4-3) are stored:
^ Check KS, Engine Coolant Temperature (ECT) sensor, Camshaft Position (CMP) sensor, EGR-temperature sensor and Throttle Position (TP) sensor common connection # 30 in ECM for contact resistance and oxidation, as well as break.

If none of the above DTCs are stored:
^ Check camshaft setting. Proceed to: CHECK CAMSHAFT SETTING section below.




CHECK CAMSHAFT SETTING
- Ignition off.
- Check camshaft setting in relation to crankshaft.
- Use gauges 999 5451, 999 5452 to check.

If camshaft setting OK:
^ Check ground lead. Proceed to CHECK GROUND LEAD section below.

If camshaft setting not OK:
^ Adjust camshaft as necessary.




CHECK GROUND LEAD
- Ignition off.
- Disconnect KS.
- Connect an ohmmeter between KS connection 2 and ground.

Ohmmeter should read approx. 0 ohms.

If value OK:
^ Check signal lead. Proceed to CHECK SIGNAL LEAD section below.

If value differs:
^ Check connector. Proceed to CHECK CONNECTOR section below.




CHECK CONNECTOR
- Ignition off.
- KS disconnected.
- Check ECM connector and 55-pin connector in central relay unit A3/F (1-4-3) or A3/D (4-3-3) connection 4 for contact resistance and oxidation.
- DTC connected.



- Connect an ohmmeter between KS connection 2 and ground.

Ohmmeter should read approx. 0 ohms.

If value OK:
^ Source of DTC is bad contact in connector.

If value differs:
^ Check lead between KS connection 2 and ECM # 30 for break.




CHECK SIGNAL LEAD
- Ignition off.
- KS disconnected.
- Connect an ohmmeter between KS connection 1 and ground.

Ohmmeter should read approx. 1 M ohm.

If value OK:
^ Test with new KS.

If ohmmeter reads infinite resistance:
^ Check connector. Proceed to CHECK CONNECTOR section below.

If ohmmeter reads approx. 0 ohms:
^ Check lead between KS connection 1 and ECM # 11 (1-4-3) or # 29 (4-3-3) for short circuit to ground.




CHECK CONNECTOR
- Ignition off.
- KS disconnected.
- Check ECM connector and 55-pin connector in central relay unit A3/F (1-4-3) or A3/D (4-3-3) connection 3 for contact resistance and oxidation.
- ECM connected.



- Connect an ohmmeter between KS connection 1 and ground.

Ohmmeter should read approx. 1 M ohm.

If value OK:
^ Source of DTC is bad contact in connector.

If value differs:
^ Check lead between KS connection 1 and ECM # 11 (1-4-3) or # 29 (4-3-3) for break.