The ESP system is the shorten word of Electronic Stability Program system. This system recognizes a critical driving condition by Yaw-rate sensor, Lateral acceleration sensor and Steering angle sensor. And then it stabilizes the vehicle by a individual wheel braking and engine torque control through CAN communication. Among components of this system, the wheel speed sensor(WSS) is the essential component of the brake system. The ESP ECU(HECU, Hydraulic and Electronic Control Unit) uses the wheel speed sensor's signals to calculate a vehicle speed and also to determine whether a wheel lock occurs or not.
The HECU monitors the wheel speed sensor's signal and If its signal is abnormally changed or the signal equivanlent to 411 km/h is detected, this DTC is set.
Item
Detecting Condition
Possible Cause
Case1
(WSS fault)
DTC
Strategy
Signal Monitoring
Poor connection
Improper installation of wheel speed sensor
Abnormal Rotor and wheel bearing
Faulty Wheel speed sensor
Threshold
value
After IG ON, when the change of a vehicle speed is over 35 km/h(21.7 mph), this monitoring is started. And the change of a wheel deceleration or acceleration is over 1.6G. Or the vehicle speed is detected as a 411 km/h(255 mph) for a certain time.
Fail-Safe
Only one wheel failure
: The ABS/TCS/ESP functions are inhibited.
The ABS/ESP warning lamps are activated, the EBD warning lamp is not activated.
More than two wheels failure
: The ABS/EBD/TCS/ESP functions are inhibited.
The ABS/EBD/ESP warning lamps are activated.
Case2
(Rotor fault)
when the signal error of a wheel speed is continuously detected 15 times at a special rotor's position
Sensor Type
Output Voltage
Tooth Count
Airgap
HIGH
LOW
Active Type
14 mA
7 mA
47 EA
0.4~1.5mm