The ABS ECU monitors the wheel speed sensor circuit continuously.
A direct current is supplied in the wheel speed sensor by a power source in the input amplifier of the control unit.
If the WSS circuit is broken, in that case a fault is detected by detecting abnormal input current. HECU cuts off the voltage supply to wheel sensor channel which had a fault and prevent vehicle's damage due to super heated harness.
If one or more defects has detected, DTC code of defected wheel will be stored. Mutual short between sensors is detected by executing self diagnosis successively at corresconding wheel when ignition ON.
Warning lamp is turned OFF unless additional faults are detected when the IG KEY is turned ON again.
Item | Detecting Condition | Possible cause |
DTC Strategy |
•
Current Monitoring | 1. Open or short of Wheel speed sensor circuit(RL) 2. Faulty Wheel speed sensor(RL) |
Monitoring Period |
•
Continuous after power up | |
Enable Conditions |
•
When the sensor current levels are out of permissible range(LOW : 7mA, HIGH : 14mA) for 200ms. - Stop control right away if wheel speed sensor failure is detected during no control | |
Fail Safe |
•
One or two wheel speed sensor fault - Only the ABS/ESP(ESC) functions are inhibited - The ABS/ESP(ESC) warning lamps are activated and the EBD warning lamp is not activated
•
More than 2 wheel speed sensor fault - The ABS/EBD/ESP(ESC) functions are inhibited - The ABS/EBD/ESP(ESC) warning lamps are activated |
