1. Wheel Speed Sensor
The wheel speed sensor is the essential component the ABS ECU uses to calculate vehicle speed and to determine whether wheel lock occurs.
For example, rear wheel speed signal is used as a referecnce value, for vehicle speed, in front wheel drive vehicles, and if a difference between front and rear wheel speed occurs, then ABS control is performed.
Wheel speed sensor is active hall-sensor type.
The ABS ECU monitors the wheel speed sensor signal continuously.
This code is set when an abnormal signal due to air gap problem or an abnormal speed change ratio are detected at the vehicle speed between 10km/h to 80km/h.
Warning lamp is turned OFF unless additional faults are detected when the IG KEY is turned ON again, and wheel speed is more than 12 Km/h.(7.4mph)
Item
Detecting Condition
Possible cause
DTC Strategy
Signal monitoring
Improper installation of wheel speed sensor
Abnormal Rotor and wheel bearing
Faulty Wheel speed sensor(FR)
Exteral noise
Case 1
(WSS signal monitoring on driving)
Monitoring Period
Continuous monitoring over 40kph(24.9mph) of vehicle speed
Enable
Conditions
When one wheel is under 2.75kph(1.7mph) and the vehicle speed is above 40kph for more than 300ms.
- Stop control right away if wheel speed sensor failure is detected during no control
Case 2
(WSS invalid signal monitoring)
Continuous
If following interference and signal disturbance is detected, a failure is set after 10s.
- Invalid signal(wheel speed changes over ±100g) occurs during pushing the brake pedal(fault monitoring duration : 20s)
- Invalid signal occurs without pushing the brake pedal(fault monitoring duration : 5s)
- Invalid signal occurs to three (of four) wheels(fault monitoring duration : 1s)
? - 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 functions are inhibited
- The ABS/ESP warning lamps are activated and the EBD warning lamp is not activated
More than 2 wheel speed sensor fault
- The ABS/EBD/ESP functions are inhibited
- The ABS/EBD/ESP warning lamps are activated
SensorType
Output Voltage
Air Gap
HIGH
LOW
Active Type
1.4~2.0V
0.7~1.0V
0.4~1.0mm