Possible causes of fault
- Communication via CAN comfort disrupted
- Problem with brake light signal from brake light switch
- Brake light relay faulty (relay carrier at left of dashboard)
- Signal lead from brake light switch faulty (open circuit, short circuit to B+ or ground)
- Fuse F38 and F26 (fuse carrier on the left)
- Brake light switch faulty
- Trailer hitch control module faulty