ASE A4 Suspension and SteeringSteering System Diagnosis and RepairHard
A vehicle with an electronically controlled variable-assist power steering system exhibits inconsistent steering effort; sometimes it feels normal, and other times it requires significant effort, even at highway speeds. There are no fluid leaks or unusual noises from the pump. A scan tool shows intermittent communication errors with the power steering control module. What is the MOST likely cause?
- AA failing power steering pump.
- BA mechanically binding steering rack.
- CA loose or corroded electrical connection to the power steering control module.
- DA faulty steering angle sensor.
Show answer & explanationAnswer & explanation
Correct answer: C. A loose or corroded electrical connection to the power steering control module.
Inconsistent steering effort on an electronically controlled system, coupled with intermittent communication errors with the control module, strongly suggests a problem with the module's power supply or communication lines, often due to loose or corroded electrical connections.
Why the other options are wrong
- A. A failing power steering pump would likely cause consistent heavy steering and/or noise, and not typically intermittent communication errors with a control module.
- B. A mechanically binding steering rack would cause consistently heavy steering and would not typically manifest as intermittent communication errors with the control module.
- D. A faulty steering angle sensor would usually cause incorrect assist or specific sensor-related DTCs, but intermittent communication issues with the *module* point to a broader electrical problem.
EPS/Variable Assist Electrical Faults
Intermittent electrical problems in electronically controlled power steering systems often manifest as inconsistent assist and communication errors.
- Commonly due to loose, corroded, or damaged wiring/connectors.
- Affects power supply, ground, or data communication.
- Leads to unpredictable system behavior.
- Often indicated by intermittent DTCs or communication errors.
Memory trick: Corroded Contacts Cause Chaotic Control.