Electric Steering Rack Warning Light Causes
The electric power steering warning light on your dashboard could come on at any time without giving any indication that something is wrong with your vehicle and could need checking out before it causes any further problems.
Low Voltage to the EPS Motor
A weak battery or a failing alternator can draw down the voltage to the EPS motor thus triggering the warning light before any other symptom appears. A battery voltage check and a test of the vehicle’s charging system would be a sensible start to diagnose an illuminated EPS warning light.
Faulty Torque Sensor
A Torque Sensor is located within the Steering Column and it determines how much effort the driver is applying to turn the steering wheel. The EPS control unit then uses this information to provide the correct amount of assistance to the driver. The sensor can be faulty and indicate an error with the EPS system. The steering may feel very sensitive or have a “jerk” feel to it. This type of fault would be picked up by a diagnostic scan of the vehicle.
Overheated EPS Motor
EPS Motor Overheating – During Low Speed Manoeuvring – Park Up for 10 Minutes – Then Drive Off. When an EPS Motor is subjected to extended low speed operation (such as repeated full lock turns when parking), it is possible for the motor to overheat. The motor’s thermal cutout will then switch off the motor until it has cooled down. The warning light will illuminate until the motor has cooled down and the park up and drive off procedure can be repeated as necessary until the fault is diagnosed.
CAN Bus Communication Fault
There are a number of other systems that communicate with the EPS control unit via the car’s CAN bus network. Faults with wiring to these modules, or with the modules themselves, can also trigger an EPS warning light. A full diagnostic scan will show a communication error.
Steering Angle Sensor Needs Recalibration
The Steering Angle Sensor needs to be recalibrated after a wheel alignment and after a battery has been disconnected. Some modern cars require a short drive to recalculate the centre of the sensor. Others can be reset using a scan tool.
Physical Damage to the Rack
Crashing into a kerb or hitting a pothole can cause serious damage to the steering rack. An inspection of the rack may reveal internal faults causing the warning light to come on. If this happens it is unlikely that a simple diagnostic reset will clear the fault.
If the light remains illuminated or your car is exhibiting symptoms of poor power assisted steering, ensure prompt specialist attention is sought and a full diagnosis completed by means of a scan tool to retrieve any logged codes and establish the cause of the problem.