Component Location
General Description
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.
DTC Description
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 fault is detected any more when the IG KEY is turned ON again, and wheel speed is more than 12 Km/h.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Signal monitoring
| Improper installation of wheel speed sensor Abnormal Rotor and wheel bearing Faulty Wheel speed sensor(RR) Exteral noise
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Case1 | Monitoring Period | The monitoring is active from 10 km/h to 80km/h and if no ABS-control is active at a front wheel and a rear wheel.
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Enable Conditions | Every time, if a gap in the wheel speed sensor signal occurs cyclically with one wheel rotation, a fault counter is increased by one. If the fault counter exceeds its limit of 10, a wheel specific fault is stored in the EEPROM.
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Case2 | Monitoring Period | Continuous
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Enable Conditions | If following interference and signal disturbance is detected, a failure is set after 10s. - non-plausible high frequency received. - non-plausible high wheel acceleration. - non-plausible high wheel jurk. - non-plausible delta T and edges at low speed.
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Fail-Safe | 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.
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Specifications
Sensor Type | Output Voltage | Air gap |
HIGH | LOW |
Active Type | 1.18 ~ 1.68 V | 0.59 ~ 0.84 V | 0.4~1.5mm |
Diagnostic Circuit Diagram
Signal Waveform & Data
Fig.1) Normal waveform of wheel speed sensor with low speed conditon