ASE A4 Suspension and SteeringSteering System Diagnosis and RepairEasy
A technician is diagnosing a vehicle with an electric power steering (EPS) system that has a warning light illuminated and a diagnostic trouble code (DTC) indicating a 'Steering Position Sensor Circuit Malfunction'. Which of the following is the MOST appropriate initial diagnostic step?
- ABleed the power steering system of air.
- BCheck the steering position sensor's electrical connections and wiring for integrity.
- CReplace the EPS control module.
- DPerform a steering angle sensor calibration.
Show answer & explanationAnswer & explanation
Correct answer: B. Check the steering position sensor's electrical connections and wiring for integrity.
When a DTC points to a 'circuit malfunction' for a specific sensor, the first logical step is always to check the physical integrity of that circuit—including connections and wiring—before condemning components or attempting calibrations.
Why the other options are wrong
- A. Bleeding the power steering system is irrelevant for an electric power steering (EPS) system, as it does not use hydraulic fluid.
- C. Replacing the EPS control module is a last resort after thorough diagnosis, not an initial step for a sensor circuit malfunction.
- D. A steering angle sensor calibration might be needed after a repair, but it won't fix a circuit malfunction. The sensor needs to communicate first.
DTC Circuit Malfunction Diagnosis
When a diagnostic trouble code indicates a 'circuit malfunction' for a sensor, the initial diagnostic step involves inspecting the electrical connections and wiring related to that sensor.
- DTCs often point to specific circuits.
- Check physical connections first.
- Wiring integrity is crucial for sensor operation.
Memory trick: Circuit fault? Check the wires, and the connections are tight!