What does it mean?
U1173 is a Network (CAN bus, module communications) fault code. It indicates: Lost Communications With Moveable Roof Module .
Symptoms
- Sunroof or folding roof does not move at all, or only in one direction
- Roof stops part way through its travel, or reverses when it reaches the end
- One touch open and close function no longer works, and the roof must be held on the switch
- Warning message that the roof system is unavailable
- Damp headliner, water marks on the trim or a musty smell in the cabin
- The roof module missing from the scan tool module list
Likely causes
- Blocked sunroof drain tubes letting water reach the module and its connector, a very common cause
- Corroded or wet connector in the headliner or at the roof frame
- Wiring broken where the harness flexes at the roof or pillar area
- Blown fuse or a poor ground for the roof module
- Roof module never initialised after a battery disconnection, a repair or a jammed roof
- Motor or position sensor fault causing the module to shut down
- Internal failure of the roof control module after water ingress
How to fix it
- Pour a small amount of water into the roof drain channels and confirm it comes out at the drain exits, then clear any blocked tubes
- Inspect the module and its connector in the headliner for water marks, corrosion and green terminals
- Check the fuse and measure supply voltage and ground at the module under load
- Test the bus wiring from the roof module to the body control module for opens and shorts
- Flex the harness at the roof and pillar transition while monitoring communication
- After repair, carry out the roof initialisation or relearn procedure, since many roofs will not operate until this is done
- Replace the roof module only once the wiring, drains and supply are proven good