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.
If power supply of the WSS input amplifier is not normal or the ABS control cycle is continued abnormally, if the exact fault location among 4 WSS can not be determined, This code is set.
Item | Detecting Condition | Possible cause | |
Case 1 | DTC Strategy |
•
Voltage motorning |
•
Improper installation of wheel speed sensor
•
Abnormal Rotor and wheel bearing
•
Faulty Wheel speed sensor |
Monitoring Period |
•
Continuous (If no under voltage, no BLS, no BLS failure is detected) | ||
Enable Conditions |
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When WSS low voltage is detected. | ||
Fail Safe |
•
Wheel speed sensor signals are not reliable. | ||
Case2 | DTC Strategy |
•
Signal motorning | |
Monitoring Period |
•
Continous | ||
Enable Conditions |
•
The monitoring reports a failure if the ABS target slip is exceeded for a time period >= 10 s at one or more wheels. - If the driver brakes or the velocity is lower than 50 km/h(31 MPH) the detection time is increased to 60s. | ||
Fail Safe |
•
Reduced function of the ESP system | ||
Sensor Type | Output Voltage | Air gap | ||
HIGH | LOW | |||
Active Type | 1.18 ~ 1.68 V | 0.59 ~ 0.84 V | 0.4~1.5mm | |
Fig.1) Normal waveform of wheel speed sensor with low speed conditon
