What does it mean?
B1607 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Headlamp Switch Input Circuit Low .
Symptoms
- Interior lamps do not come on when the doors are unlocked or opened
- Interior lamps stay on and drain the battery
- The fade-in and fade-out effect no longer works and the lamps switch abruptly
- Courtesy lamps work from the dome switch but not from the door or the remote
- On the lighting variant, the headlamps come on by themselves or the switch positions no longer match their markings
Likely causes
- Faulty door latch or ajar switch that provides the illuminated entry request
- Keyless entry receiver not passing the unlock request to the module
- Chafed or partly broken input wire, most often in a door hinge boot
- Corroded or loose connector at the module or at the interior lamp circuit
- Interior lamp or dimming driver circuit fault preventing the fade function
- Module input stage failure
- On applications where this code refers to lighting control, a headlamp switch input reading low from worn contacts or a short to ground
How to fix it
- Watch the illuminated entry and door ajar status in live data while unlocking with the remote and opening each door in turn
- If the request never appears, test each door latch switch individually to find the one not reporting
- Jumper the input at the module connector to confirm the module still reacts, which separates the module from the input circuit
- Inspect the loom in the door hinge boot, flexing it while measuring continuity
- Check the interior lamp fuse, supply and ground before assuming a module fault
- Repair the wiring or replace the failing latch, and leave the module for last
- On the lighting variant, back-probe the headlamp switch input in each position and ohm the switch for a permanent low reading