P0635 the electric power steering has a malfucntion

­­­­­Fault code P0635 the electric power steering has a malfunction stored in the control module memory. When the control module stops functioning properly as per the requirements. In Mercedes, an electric power steering control system is used to control the steering system. There is the complete assembly of the steering system installed in the middle of the steering rack. In this complete assembly steering control module, steering motor, and torque sensor are installed. When any one of these fails to function properly, then this kind of fault code is stored in the control module.

When the driver turns the steering wheel, the torque sensor senses the torque applied to the steering wheel. Send this signal to the control module according to which control module turns ON the steering motor to turn the steering left or right accordingly.

Causes of:

Faulty steering control module.

Failure of steering torque sensor.

Faulty steering electric motor.

Blown fuse or damage wiring harness of the sensor.

Software issue in the contorl module.

Symptoms:

The steering warning light will start illuminating on cluster meter.

Fault code store in control module.

steering operation become hard to steer.

How to trouble shoot:

Case#1:

When this fault code P0635 the electric power steering is stored in the control module, it means that there is some electric problem in the electronic control system. To know what the problem is you need to check the fault code stored in the control module. Hook up the scan tool to check the fault code, if the fault code stored in the control module indicates a problem with the steering control module. Then you need to check something before replacing the steering control module. Like the wiring harness, fuse and relay of the steering control module check the ground wire of the steering control module. Sometimes ground wire of the control module gets disconnected from its original position. Due to this steering control module stopped functioning. If the fuse, wiring harness, and all the other things are good. Then you need to change the electronic steering control module.

Case#2:

If the fault code stored in the control module indicates a problem with the steering torque sensor. Then you need to check the steering torque sensor with the help of a scan tool. Check the reading of the steering torque sensor by turning the steering wheel left or right. Meanwhile, check the reading in the scan tool if the reading of the torque sensor increases or decreases when the steering wheel is turned. If the reading does not increase or decrease when the steering wheel is turned left or right. Then it means that the steering torque sensor is not working properly. In this situation, you need to replace the steering torque sensor. You can’t replace the steering torque sensor only, as it is fitted inside the steering. You will need to change the complete steering set to get out of this fault code.

Case #3:

 When fault code stored in the control module indicates a problem with the electronic steering motor. Then you need to check the electronic steering motor. Check if the motor starts rotating when the steering wheel is turned by the driver. If it does not rotate when the steering wheel is turned then it means that the motor is faulty. Only the electric steering motor is not replaceable, you need to replace the complete steering assembly.

How serious is this problem:

This problem could be considered very risky as it is the problem of faulty steering operation. When the steering operation is not proper, while driving you might feel a hard steering operation. It could be also possible that sometimes steering becomes very hard to turn the steering. In this kind of situation, you might get met with a major accident. Because of the steering not turning at the required time. In this case, you need to repair or replace the complete steering set. So that this kind of does not affect your driving experience.

Special note:

When there is a steering warning light starts flashing on the cluster meter. Stop driving and visit the nearest workshop to know the reason behind this warning light. Before replacing any part of the electronic steering. Go through all the above procedures to know what the exact faulty part is in the electronic steering control system. Sometimes it might be possible that this warning light starts flashing on the cluster meter. Due to some software issues inside the control module.

What was in our case?

In my case, the steering warning light was illuminating the cluster meter again and again. After driving a certain kilometer, the power steering light starts illuminating on cluster meter. When we scanned the vehicle we found a fault code stored in the control module. In Mercedes, the steering control module is located at the steering rack.

 After checking all the wiring harnesses and ground wire of the steering control module. We did not find any damage wiring harness related to the steering control module. Then we check the fuse related to the steering control module.

Then we replace the completer steering control module along with the rack. After coding and the steering calibration vehicle started running very fine. There was no warning light illuminating at the cluster meter while driving. Also, there was no fault code stored in the control module after replacing the complete steering rack.

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