P1669

SIGNAL, TCS ACTIVE





Fault Symptom.
Marginal effect on emissions.

Conditions.
No test signal from the TCS when starting or TCS active signal constantly high or its pulses are longer than 2.5 seconds.

Diagnostic Help.
The function between the TCS and Motronic system can be checked with the ISAT scan tool.
- Select "TCS".
- Select "ACTIVATE".
- Select "DISCONN ENRICHMENT".

The TCS then sends a signal, B+, for disconnection of full-load enrichment.

Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the wiring at several points and in different directions to ascertain whether the wiring harness, including any connectors, is causing the trouble. Observe the multimeter, ISAT scan tool or test lamp while doing this.





Diagnostic Procedure.
1. Check for additional diagnostic trouble codes
- Use the ISAT scan tool to obtain readouts of all diagnostic trouble codes in the TCS.
- In particular, look for diagnostic trouble codes B1406, B1407 or B1408. These diagnostic trouble codes light up the TCS OFF lamp.

Does the ISAT scan tool show any TCS diagnostic trouble codes?
YES: Deal with the diagnostic trouble codes in the Traction Control System.
NO: Continue with point 2.

2. Check the TCS signal
- Start the engine and run it at idling speed.
- Select "TCS".
- Select "ACTIVATE".
- Select "DISCONN ENRICHMENT".

The TCS control module sends a battery positive (B+) signal for disconnection of full-load enrichment. The Motronic system interprets this as fuel shut-off and stops the engine.

Has the engine stopped?
YES: Continue with point 5.
NO: Continue with point 3.





3. Check the lead between the TCS and the Motronic control module
- Check the lead between pin 68 of the Motronic control module and pin 21 of the TCS control module for continuity

Is the lead OK?
YES: Continue with point 4.
NO: Repair or replace the lead. Then continue with point 5.

4. Check the TCS control module's output signal
- Remove the Motronic control module.
- Connect a voltmeter to pins 68 and 28 of the control module's connector.
- Select "TCS".
- Select "ACTIVATE".
- Select "DISCONN ENRICHMENT".

In the "ON" position a reading of about 12 V should be obtained.

In the "OFF" position a reading of about 0 V should be obtained.

Are the voltage readings OK?
YES: Continue with point 5.
NO: Continue fault diagnosis in the Traction Control System.





5. Final check

- Clear the diagnostic trouble code.
- Implementation of driving cycle:
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Evaluation of driving cycle:
^ Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?
YES: Continue at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO: The steps taken to rectify the fault were correct.