What does it mean?
B1377 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Inside Tailgate Switch Circuit Malfunction .
Symptoms
- The inside close button does nothing when pressed
- If the switch is shorted the tailgate can start to close as soon as it is opened, which is a pinch hazard
- Power close may be blocked from every control while the false request is present
- A beep or message each time the button is used
- The tailgate can still be closed by hand
Likely causes
- Inside tailgate switch worn or stuck, so the request never clears
- Water running down the inside skin of the tailgate onto the switch after the vapour barrier was disturbed
- Chafed switch wiring where the harness enters the tailgate trim panel
- Connector disturbed or half-fitted after lock, wiper motor or trim work
- Switch feed shorted to ground, which the module reads as a button held down
- Broken conductor in the flexing part of the tailgate harness
- Input stage fault in the tailgate control module
How to fix it
- Watch the inside switch input on the scan tool while pressing it, and also with nobody touching it, to catch a stuck signal
- Remove the tailgate trim and inspect the switch, its connector and the wiring entry point for damp and chafe
- Check the switch for continuity only while pressed; replace it if it stays closed or is intermittent
- Check the switch circuit for a short to ground with the switch unplugged
- Flex the harness in the hinge boot while monitoring, since the same loom feeds several tailgate inputs
- Dry the tailgate cavity and repair the vapour barrier so the fault does not return
- Replace the control module only after the switch and its wiring are proven good