PRE-RELEASE
Rear-wheel sensors
| Rear-wheel sensors |
The rear left wheel sensor sends a wheel speed signal to pin 9 on the control module. The sensor is grounded via pin 8.
The rear right wheel sensor sends a wheel speed signal to pin 2 on the control module. The sensor is grounded via pin 1.
The wheel sensors are integrated into the wheel hubs and consist of an inductive sensor with 29 teeth.
The inductive sensor works like a small alternator, the sine-wave voltage of which increases with increasing wheel speed. The sine-wave voltage alternates between positive and negative polarity, which is achieved by alternate teeth and gaps on the toothed wheel.
The design of the rear-wheel sensor is different to that of the front-wheel sensor, and the sensor is less sensitive to play in the wheel bearings. With a multimeter set for AC voltage connected between the two leads of the sensor, a reading of >100 mVAC should be obtained when the wheel is rotated one revolution per second.
A wheel speed of 20 km/h gives about 5 VAC.
The control module uses the frequency to measure the vehicle speed.
Diagnostics
If there is a break in the rear left circuit, diagnostic trouble code C1382 is set, the ABS function is disabled and the ABS warning lamp lights up.In the event of a mechanical fault or malfunction in the rear left circuit, diagnostic trouble code C1381 is set, the ABS function is disabled and the ABS warning lamp lights up.
If there is a break in the rear right circuit, diagnostic trouble code C1387 is set, the ABS function is disabled and the ABS warning lamp lights up.
In the event of a mechanical fault or malfunction in the rear right circuit, diagnostic trouble code C1386 is set, the ABS function is disabled and the ABS warning lamp lights up.
