The Wheel Speed Sensors (WSS)are an essential component the ABS system. The WSS signals are used to calculate vehicle speed and to determine whether wheel lock occurs.
The Wheel Speed Sensors are active hall-sensor type.
The ABS ECU monitors the wheel speed sensor signal continuously.
This code is set when the sensor air gap is out of specified range or when the ABS control cycle is continued abnormally.
The HECU checks for air gap malfunctioning by monitoring the sensor signal at speeds between 2Km/h to 10 Km/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 10 Km/h (6.2mph).
Item | Detecting Condition | Possible cause | |
DTC Strategy |
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Signal monitoring | 1. Improper installation of wheel speed sensor 2. Abnormal Rotor and wheel bearing 3. Faulty Wheel speed sensor | |
Enable Conditions | Case 1 (LargeAir-Gap) |
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When the minimum wheel velocity is 2kph(1.2mph) and the velocity of other wheels exceed 10kph(6.2mph) with the acceleration of < 0.4g, the condition is continued for 154ms.
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When the velocity of more two wheels is 2kph(1.2mph) and the max. wheel velocity exceeds 10kph(6.2mph) with the acceleration of < 0.4g, the condition is continued for 20 sec
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The conditions above with the acceleration of > 0.4g, failure detection time is 2 minutes.
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After velocity of 4 wheels exceeds 10kph(6.2mph), if the velocity of 1 wheel or 2 wheels is below 2kph(1.2mph) for 12 seconds | |
Case 2 (long term ABS mode) |
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During the ABS control cycle, if the wheel velocity of 2km/h (1.2mph) is lasted for more than 12sec.
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If the ABS control cycle is continued for more than 36sec. | ||
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 conditon
