ESP_a139_steeringAngleWrongSign

Steering Wheel Position Sensor: Plausibility fault.

Live incidence rate

<0.01% (Extremely rare)

Vehicle messages

None displayed

Impact

May fault VDC/TC, ABS performance degradation

Description

Steering Wheel Position Sensor: Plausibility fault.

Cause

This monitoring detects a wrong sign of steering angle signal. The yaw rate calculated from steering angle and the yaw rate calculated from the wheel speed sensors are compared. If the measured yaw rate fits to the model yaw rate positive integrals (IVzLwVA and IVzLwHA) are calculated but if the negative values fits the integrals will become negative. A fault is determined if the integral value is negative and forward driving is recognized. This fault will cause a release test in the following ignition cycle to assure that the sensor is build in correctly. This fault can also be caused by swapped WSS lines at one axle. It requires a release check in the following ignition cycle to prevent system release when the fault is still present. The conditions for release is positive integrals (IVzLwVA and IVzLwHA) > +180 deg.

Clear condition

Verify EPAS is awake, in good state, and there is traffic present on the bus. Review EPAS/DI alerts for other indicators of failure

Models

Cybertruck, Model 3 2017-2023, Model 3 2024+, Model S 2021+, Model X 2021+, Model Y, Model Y 2025+

Visibility

service

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