What does it mean?
U1048 is a Network (CAN bus, module communications) fault code. It indicates: No Communication With Rear Wheel Steering Control Module .
Symptoms
- Rear wheel steering warning lamp or a chassis system message on the display
- Rear wheels no longer steer, so the turning circle becomes noticeably larger
- Vehicle feels less stable or vaguer during lane changes at speed
- Steering may feel heavier or the assistance level changes
- Scan tool cannot find the rear steering module while other modules respond
- Related stability or chassis codes stored in other modules
Likely causes
- Blown fuse or failed relay in the rear wheel steering module supply
- Corroded or water damaged module connector, since the unit is mounted at the rear of the vehicle and exposed to spray
- Open circuit in the bus wiring running along the underbody to the rear of the car
- Poor or corroded ground at the rear module mounting point
- Internal module failure or a burnt actuator driver stage inside it
- Harness damage from road debris, a rear impact or corrosion at an underbody connector
- Rear steering actuator shorted, taking out the module supply
How to fix it
- Confirm which modules on the same bus still communicate; if only the rear module is missing, the fault is local to it
- Check the fuses and relays supplying the rear steering module and test them under load
- Inspect the module connector at the rear of the vehicle for water, corrosion and damaged seals
- Measure supply voltage and ground at the module with the ignition on, using voltage drop tests
- Follow the underbody harness looking for road damage, chafing and corroded inline connectors
- Test the bus lines from the rear module forward to the gateway for continuity and shorts
- Check the rear steering actuator circuits for a short that could have damaged the module
- Replace and calibrate the rear wheel steering module only when supply, ground, wiring and actuator have been proven good