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B1371

Symptom: TCS OFF lamp on, TCS symptom inoperative

B1371

Wheel speed FL, signal incorrect or absent.


Fault symptom

TCS OFF lamp on, TCS symptom inoperative

Condition

Wheel speed signal incorrect or absent, or indicates a speed higher than 280 km/h.



Note

The trouble code for wheel speed signals can be generated when the brakes are tested (in connection with annual vehicle inspection, for instance) or if the car is started on a slippery uphill gradient so that the front wheels spin and the rear wheels remain stationary.

If only one wheel spins and the other three remain stationary, the control module cannot tell whether the speed signals from the three stationary wheels are correct or false. In such case, trouble codes are generated for the three stationary wheels. These trouble codes are cleared automatically, however, as soon as the signals return.

If wheelspin continues for more than 20 seconds while one of the wheels remains stationary the whole time, the TCS system will be disconnected and the TCS OFF lamp will come on. To restore the TCS function, the ignition must be turned off and then on again.


Diagnostic procedure



1. If the ANTI LOCK lamp also lights up, obtain readings of any trouble codes in the ABS system and take the necessary remedial action, see Service Manual 5 Brakes.

2. Connect the ISAT. Drive the car slowly (but at least 3 km/h) and select WHEEL SPEED FL in the "OBTAIN READINGS" menu to check whether wheel speed is displayed.


If it is not, connect a BOB and check whether a wheel speed signal is present on pin 25 when the LH front wheel is rotated at a speed of about 1/2 revolution per second. The correct reading is about 15 Hz.

If the reading is not correct, check the cable between pin 25 of the TCS control module and pin 17 of the ABS control module for continuity/shorting. Remedy any defective cable.




3. Clear the code diagnostic trouble code. Start the car and drive it on test to check whether the diagnostic trouble code recurs. If it does, see "Before replacing a control module" for further measures.