C059A — Power Steering Control Module - Rear Missing Calibration

Causes

• Rear power steering control module erased, not programmed, or lost calibration data
• Failed software update or interrupted programming procedure
• Module battery voltage issues during programming (low voltage or spikes)
• Corrupted non-volatile memory in the steering module
• CAN bus/communication errors preventing calibration confirmation
• Faulty steering angle sensor or wheel speed inputs used during calibration

Symptoms

• Vehicle displays power steering warning lamp or EPS/PS fault message
• Reduced or lost rear steering assist or altered steering feel
• Steering may default to a safe/limited-assist mode
• ABS or stability control warnings if modules share sensors/data
• In some vehicles, steering calibration prompts or re-learn required message
• Possible steering torque inconsistencies or drift

What to check

• Verify vehicle battery charge and health; ensure stable battery voltage (12.4–12.8 V at rest) during tests
• Scan for other DTCs (C-codes and U-codes) that indicate comms or sensor issues
• Confirm part number/part provenance if module was replaced recently
• Visually inspect connectors and wiring at the rear PSCM for damage, corrosion, or loose pins
• Check CAN/LIN bus integrity: continuity, termination resistances and absence of shorts
• Verify steering angle sensor, wheel speed sensors, and associated grounds are functioning

Signal parameters

• Rear PSCM supply voltage: typically battery voltage (expected ~11–14 V during key-on/run)
• CAN bus activity: module should transmit/receive steering and status frames (check ID presence)
• Module internal software version and calibration flags accessible via OEM tool
• Steering angle input values: should change with wheel rotation and be within sensor range
• Wheel speed inputs used for calibration: expected 0–vehicle speed values consistent with vehicle motion
• Fault counters/last calibration timestamp stored in module memory

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