What does it mean?
B1677 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Passenger Courtesy Lamp Control Circuit Low .
Symptoms
- Passenger courtesy or footwell lamp does not light when the door is opened
- The lamp stays on continuously and contributes to overnight battery drain
- Interior lighting fuse blows and other interior lamps fail with it
- Illuminated entry and the delay function stop working on that side
- The lamp flickers when the passenger door is moved on its hinges
Likely causes
- Short to ground in the passenger door wiring, most often inside the flexible boot between the door and the body where individual wires break and touch the door shell
- Water tracking down inside the passenger door and reaching the lamp wiring or connector
- Corroded or crushed lamp holder in the door trim, the footwell or under the glove box
- Wire pinched by a trim clip, a screw or a seat rail bolt during previous work
- Additional interior lighting connected to this circuit
- Damaged wiring in the door sill area, where the loom is exposed when trim is removed
- Shorted lamp output driver inside the body control module
How to fix it
- Open and close the passenger door while watching the courtesy lamp status and the door ajar input on live data
- Unplug the courtesy lamp and check whether the code still sets, which separates the lamp from the wiring
- Pull back the rubber boot at the passenger door hinge and flex the wires by hand, looking for cracked insulation and exposed copper
- With the lamp disconnected, measure the resistance from the control wire to ground; a low value proves a short to ground
- Check under the sill trim and behind the glove box for wiring damaged by clips, screws or previous repairs
- Disconnect any added interior lighting and see whether the fault clears
- Repair the broken wires with staggered, insulated joints, then operate the door repeatedly to confirm the code does not return