ABS

Fig. 15 Codes B1371 & B1372: Wheel Sensor Front Left, Signal Faulty Or No Signal:

Symptom
ABS warning lamp is lit ABS inoperative

Condition
Fault is recorded in case of break of continuity after max. 150 milliseconds both when the car is stationary and when the car is being driven. Fault is recorded in case of faulty signal after max. 20 seconds at a speed> 10 km/h.

Action
1. Raise the car, and check wheel sensor for front left wheel with ISAT command "WHEEL SPEEDS" on the "OBTAIN READOUTS" menu.
- All four wheel speeds are shown on the display.
- Rotate the front left wheel by hand. The ISAT display must show approx. 5 km/h

- If the values are correct go to item 4.
- If the the values are incorrect, continue with the next item.

2. With the ignition turned off, connect the BOB to the cable connector of the ABS unit. Rotate the front left wheel at 1rev./sec, and measure the AC voltage between pins 4 and 5. The correct value must be greater than 100mV. The voltage must increase with wheel speed. If the values are correct, go to item 4. If the values are incorrect, continue with the next item.

3. Check the resistance in the wheel sensor by measuring between pins 4 and 5. The correct resistance must be 0.8-1.7 KOhm. If the values agree, check the distance between the wheel sensor and the rear gear. Check the gear wheels for signs of damage. Check the wheel bearing clearance as well. If the resistance is correct, check the wire between pins 4 and 5 of the ABS unit and the wheel sensor for break in continuity or short circuit. Replace the wheel sensor if necessary.

4. If no faults have been discovered despite the above checks, clear the fault codes, test-drive the car and see whether the fault codes re-appear