Unfortunately I didn't find any TSBs but this is an issue most likely in the wiring. Dim lights are caused by resistance in the circuit.
What I would suggest is unhooking the wiring from the bulb to the fuse block and then to the switch and measuring resistance for each wire. This is done by putting one lead of the meter at one end of the wire and the other lead at the other end. Then set you meter on ohms and you should have about a half ohm of resistance on wiring.
It is most likely not a ground wire because this is what is called ground side controlled. That means all the control components (switch and BCM) are after the bulb in the circuit. So basically when you switch off the headlamps it just opens the ground circuit and breaks the circuit and turns the lights off.
Let me know if you have questions and we can work through it.
https://www.2carpros.com/articles/how-to-check-wiring
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Feb 29, 2020 at 8:40 AM
