What does it mean?
U1143 is a Network (CAN bus, module communications) fault code. It indicates: Lost Communication With Power Sliding Door Module-Left .
Symptoms
- Left sliding door will not operate from the switch, the remote or the handle, and can only be moved manually
- Door stops part way, reverses on its own or closes with unusual force
- Warning chime or a message that the power door is disabled
- Door ajar warning stays on with the door closed
- Interior lamps staying on and draining the battery
- The sliding door module is missing from the scan tool module list
Likely causes
- Broken conductors in the flexible harness that runs to the sliding door, which is bent every time the door opens; this is the most common cause
- Corroded or wet connector in the B pillar or in the door itself, often after water runs down the track
- Blown fuse or a failed power feed and ground at the sliding door module
- Open or shorted bus wiring between the door module and the body control module
- Door motor, clutch or latch fault that makes the module shut down to protect itself
- Binding rollers, a bent track or a damaged cable that overloads the drive
- Internal failure of the sliding door control module
How to fix it
- Open and close the door slowly while watching the module on the scan tool to see when communication drops
- Peel back the loom on the sliding door harness at the hinge and track area and check every conductor for breaks and stretched insulation
- Inspect the pillar and door connectors for water, corrosion and pushed-back terminals
- Check the fuse, supply voltage and ground at the door module while the circuit is loaded
- Test the bus wiring from the module to the body network for opens and shorts
- Inspect the track, rollers, cables and latch for binding, then clean and lubricate as required
- Replace the sliding door module last, and carry out any required door initialisation or relearn afterwards