Signal monitoring

Improper installation of wheel speed sensor

Abnormal Rotor and wheel bearing

Faulty Wheel speed sensor(RL)

Continuous (the conditions below are met and no under voltage is not detected)

If one (or two) wheel are at 2.75km/h and the other wheels are above 12 km/h for longer than 1s.

During driving, when the vehicle accelerates 18km/h after a particular wheel speed gets to 2.75km/h and stays there. At that time, If one (or two) wheel are at 2.75km/h.

- This monitoring is performed at the vehicle is accelerated to 12km/h

a) once after energizing the system.

b) If the vehicle was stationary for approx. 2s.

If one (or two) wheels are under 5km/h and the two fastest wheels have a velocity above 12km/h for more than 20s.

- This monitoring is performed continuously.

Continuous ( If vehicle speed > 12 m/s (43,2 km/h ) )

- but this monitoring is disabled in the following event

1. aquaplaning.

2. interference.

3. supply voltage below 7.1 or above 18 Volts.

No wheel speed signals within 10 ms to 20 ms at a vehicle speed > 12 m/s (43,2 km/h ).

- If the dynamic sensor monitor resconses, the failures will be stored into failure memory immediately after a waiting period of 60ms.

- If occurs low voltage active sensors during the waiting period of 60 ms no failure is stored in the EEPROM.

Continuous

Vehicle < 100Km/h

- Difference of two wheel speeds at FL to RL/FR to RR>1.7m/s (6km/h).

- Difference of two wheel speeds at FL to FR/RL to RR>1.7m/s + 1.1m/s.

- Difference of two wheel speeds at FL to RR/FR to RL>1.7m/s + 2.2m/s.

? If at least one wheel is at 1.4m/s or lower, a wheel speed difference of adjoining wheels up to 3.3m/s(or 3.3m/s + 1.1m/s) is permitted.

Vehicle > 100Km/h

- Difference of two wheel speeds at FL to RL/FR to RR>(6%×Vref).

- Difference of two wheel speeds at FL to FR/RL to RR>(6%×Vref + 1.1m/s).

- Difference of two wheel speeds at FL to RR/FR to RL>(6%×Vref + 2.2m/s).

? V_ref : Vehicle Reference Speed difference and additional conditions as shown below.

1. 18s - if fault threshold is exceeding > 1.7m/s resp. 6%

2. 9s - if fault threshold is exceeding > 3.3m/s resp. 12%

3. If any wheel shows strong deceleration the fault detection filter time is not shorter than 18s.

4. If spinning wheel is detected the fault detection filter time is not shorter than 72s.

Fault allocation

If the exact fault location can be determined the wheel specific fault will be set. This is the case if at the time of detection the faulty wheel speed is at or below 1.4m/s.

Otherwise a general WSS_Generic fauly (C1213) is set.

Detection filter time

- Response and detection filter time depend on the amount of the speed

Main Monitoring

- The main monitor needs additional information of the ESP-sensors and is active for a velocity > 20 km/h and no under voltage is detected.

Backup Monitoring

- Continuous

Main Monitoring

1. If the maximum difference of wheel speeds related to maximum wheel speed exceeds 5%.

2. detection filter time :

- the above conditions apply for 20s for 1 defective wheel speed sensor.

- the above conditions apply for 40s for 2 defective wheel speed sensor.

Backup Monitoring

1. If the deviation between the fastest and the slowest wheel exceeds 6% related to the fastest wheel when the velocity is higher than 50 km/h.

2. When the velocity is below 50 km/h, if the deviation exceeds an absolute value of 3km/h.

3. detection filter time : normally 20s

- In case of a detected curve, the threshold is increased with an additional value of 4 km/h.

Sensor failure outside of the ABS control cycle

1. 1~2 wheel failure

- Only the ABS/ESP functions are inhibited.

- The ABS/ESP warning lamps are activated and the EBD warning lamp is not activated.

2. More than 3 wheels failure

- The ABS/EBD/ESP functions are inhibited.

- The ABS/EBD/ESP warning lamps are activated.

Sensor failure inside the ABS control cycle

1. 1~2 wheel failure

- The ABS/ESP functions are inhibited after end of control.

- The ABS/ESP warning lamps are activated and the EBD warning lamp is not activated.

2. More than 3 wheels failure

- The ABS/EBD/ESP functions are inhibited.

- The ABS/EBD/ESP warning lamps are activated.

? Control of the corresponding wheel is no longer possible. If a sensor fault occurs on a front wheel, pressure is increased; on a rear wheel, pressure is decreased.