• Motor damaging controller: After doing failure analysis on the rack motor/actuator there are 2 issues that can lead to burning up the internal MOSFETs of the controller.
  1. Power supply issue to the motor, or bad/intermittent motor.
  2. When a fault is detected the controller loads all 3 motor phases with 8 Amps to help control the rate returning to center. However, if the fault prevents it from knowing where center is then it loads all 3 phases continuously creating a lot of internal heat in the controller. Even though the Amps are not great compared to the motors potential and the load is pulse width modulated it is harder on the system because it’s continuous without even reversing polarity. Under normal operation the phases are excited for very short durations.

I can appreciate the efforts slowing the return rate to center but it’s unclear why it’s dependent on electronics at a time of electrical failure. We know the rear steering fail-safe relies on the internal belleville spring washers to ‘mechanically’ keep the wheels centered so if you know your rack is okay and your driving with an electrical fault for any length of time it is best to pull the 4WS fuses.

• Some faults disable most digital data in the Scan Tool leading to errors in diagnosing: There are certain instances the scan tool displays faulty data, such as 1-2 battery volts, Steering wheel angle A and/or B freezes, Steering wheel index/marker pulse shows low but should be HIGH between -10 to +10 degrees amongst others. It is mentioned briefly under DTC C0455 but doesn’t require 0455 to cause that. It also mentions incorrect info about 12v ref but what’s important is to realize most of the scan tool data is useless when the controller grounds out some of these signals. You can easily identify when this occurs by viewing the obvious flaky battery voltage. Check continuously while using the scan tool.