CVU piston position outside valid range
If the fault is active: 1. Check for other active OR passive DTCs, that could explain the root cause. - Fix the root cause (that DTC is set passive). 2. Perform a Diagnostic SelfTest (requires Parking Brake to be applied) - If the root cause fault has been fixed, this DTC will be set passive. - If the fault has not been fixed/found, the SelfTest may give a better explanation of the root cause (other DTC with better fault indication will be created). 3. Let the Diagnostic SelfTest try to reset the piston position to valid area. 4. Confirm that Diagnostic SelfTest completed succesfully. - Test drive the vehicle, at speeds below 30 km/h, by turning the steering wheel from side to side. Ceck if the fault reappears. Exteended testing 1. Set system in service mode. 1. Turn the ignition key to OFF, and wait for 10 seconds. 2. Turn battery master switch off (if not available - remove negative battery pole connector), and wait for 10 seconds. 4. Turn battery master switch and ignition key ON. 5. Manually align axle so it points forward. 6. Make sure axle can operate/move without any danger for personal or vehicle. 7. Inactivate Service Mode. 8. Let self test complete and demand a exteended self test. 9. Confirm that Diagnostic SelfTest completed succesfully. - Test drive the vehicle, at speeds below 30 km/h, by turning the steering wheel from side to side. Check if the fault reappears. • If the fault remains: - Check the CVU::CPS by turning the tag axle wheels from side to side, while monitoring the signal Piston Postion. If the signal value is implausible repair/replace the CVU. Otherwise the faulty component might be the MPU. Check for available software updates/campaigns.
What you'll see
No driver-visible symptom recorded.
System reaction
Red Steer tag axle fault warn EST in released mode
Diagnostic depth
The fault is validated as present if the piston position is outside valid range.
• Software flaws • CVU mechanical failure (magnet ring for CPS has come loose) • Handling the EST system forced piston outside valid range.