B1406

Fault Symptom
TCS OFF lamp on, TCS system inoperative and possibly trouble codes in MOTRONIC.

Condition
For trouble code B1406: Main throttle butterfly position signal from pin 54 of the MOTRONIC control module to pin 11 of the TCS control module incorrect.
For trouble code B1407: Main throttle butterfly position signal from pin 54 of the MOTRONIC control module to pin 11 of the TCS control module shorted to ground.
For trouble code B1408: Main throttle butterfly position signal from pin 54 of the MOTRONIC control module to pin 11 of the TCS control module shorted to battery + or no continuity.

Diagnostic Procedure
1. If the CHECK ENGINE lamp (MIL) is also on, obtain a reading of the trouble codes in the MOTRONIC system.
2. Connect the ISAT (scan tool) and select "MAIN THROTTLE POS" in the "OBTAIN READOUTS" menu. Drive the car and check that the ISAT (scan tool) shows about 9% at idling speed and about 70-92% at full throttle.
3. If it does not, switch off the ignition and connect a BOB to the TCS control module. Start the engine and check whether the main throttle butterfly's position signal is present on pin 11 so that a reading can be obtained.
Correct readings are about 1.2 V when idling and about 2 V at 2500 rpm.
If the readings are incorrect, check the cable between pin 11 of the TCS control module and pin 54 of the MOTRONIC control module for continuity/shorting.
4. Remedy any defective cable.
5. Clear the trouble codes, if any. Start the car and drive it to check whether the code is generated afresh.
- If it is then see preliminary diagnostic information.