What does it mean?
B1669 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Reverse Lamp Control Circuit Open .
Symptoms
- Neither reverse lamp lights when reverse gear is selected
- No warning of movement to people behind the vehicle when reversing, which is a safety concern
- Dark reversing camera image at night
- Lamp failure message displayed in the cluster
- The fault appeared immediately after rear body work, towbar fitting or a lamp replacement
Likely causes
- Both reverse lamp bulbs burned out, which happens easily because they always work as a pair
- Reverse lamp connector left unplugged after bumper, trim or towbar work
- Broken control wire in the rear harness, most often in the section that bends with the tailgate
- Terminal pushed out of the connector body so the plug looks connected but is not
- Corroded lamp holder that has lost all contact with the bulb base
- Missing configuration in a replaced control module, so the output is not enabled
- Open output stage inside the module itself
How to fix it
- Select reverse and confirm neither lamp works, which points to a shared cause rather than a single bulb
- Check the fuse and confirm the reverse signal is present, since the module must first know that reverse is engaged
- Inspect both bulbs and holders, then verify that the lamp connectors are plugged in and locked
- Command the reverse lamps on with a scan tool where possible and measure the voltage at the lamp connector
- With the circuit off, check continuity of the control wire between the module and the lamp to locate the open
- Give special attention to the tailgate flex loom and the body grommet, moving the wiring while measuring
- Repair the broken wire or terminal, refit correct bulbs, and check module configuration only if the wiring proves good