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.
The Wheel Speed Sensors are active hall-sensor type.
The ABS ECU monitors the wheel speed sensor circuit continuously.
If the sensor signal current is continuously out of the specified range for 140msec, then the HECU determines that the circuit is open/short, and sets this code.
Warning lamp is turned OFF unless additional faults are detected when the IG KEY is turned ON again, and wheel speed is more than 10 Km/h (6.2mph).
Item | Detecting Condition | Possible cause |
DTC Strategy |
•
Current Monitoring | 1. Open or short of Wheel speed sensor circuit 2. Faulty Wheel speed sensor |
Enable Conditions |
•
When the sensor signal current is continuously out of the specified range of 4mA ± 10% ~ 22mA ± 10% for 140msec. | |
Fail Safe | 1) Only one wheel failure : Inhibit the ABS/ESP/DBC control, allow the EBD control. The ABS/ESP/DBC warning lamps are activated, the EBD warning lamp is not activated 2) More than two wheels failure : The ABS/EBD/ESP/DBC functions are inhibited. The ABS/EBD/ESP/DBC warning lamps are activated |
Sensor Type | Output Voltage | Air Gap | |
HIGH | LOW | ||
Active Type | 1.4V | 0.7V | 0.4~1.5mm |
Fig.1) Normal waveform of wheel speed sensor with low speed condition
- High : approx. 1.4V, Low : approx. 0.7V
Fig.2) Normal waveform of smart type wheel speed sensor with standing still
※ Smart type wheel speed sensor is applied to the rear wheel speed sensor of the vehicle equiped SPAS.
Fig.3) Normal waveform of smart type wheel speed sensor with moving condition.
