Combination Switch & BCM Hack for Constant Turn Signal Current
Combination Switch & BCM Hack for Constant Turn Signal Current
I need some electronic help to pull off a headlight mod I have been working on for my 2004 G35 coupe. I am hoping that one of you out there might have the knowhow I am lacking. I have all the components to make a chasing/scanning LED turn signal light (think Knight Rider) in the clearance strip of the headlights, but to do so I need to have the turn signal's electrical current come to the headlights in a constant stream and not in blinks/flashes/pulses, like it currently does.
Here is a video of lighting similar to what I am trying to do in the clearance strip:
I have done a bunch of research and I know that the combination switch sends a signal to the body control module (BCM), and the BCM is what sends out the flashing signal to the turn signal bulbs. I am assuming I can tap into the correct wiring coming from the combination switch before it goes into the BCM and reroute the signal to the headlights in the form of a constant current. The combination switch is what is worrying me. It is not just a simple on/off switch.
Looking at the diagrams below, I see that I need to do something with the following wires, but I am not sure what:
- OUTPUT 1 (Y)
- INPUT 4 (G) – Left Turn Signal
- INPUT 5 (G/R) – Right Turn Signal
Can anyone shed some light on this for me?
Here are the relevant diagrams from the factory service manual (FSM):
BCS-3

LT-110

LT-111
Here is a video of lighting similar to what I am trying to do in the clearance strip:
I have done a bunch of research and I know that the combination switch sends a signal to the body control module (BCM), and the BCM is what sends out the flashing signal to the turn signal bulbs. I am assuming I can tap into the correct wiring coming from the combination switch before it goes into the BCM and reroute the signal to the headlights in the form of a constant current. The combination switch is what is worrying me. It is not just a simple on/off switch.
Looking at the diagrams below, I see that I need to do something with the following wires, but I am not sure what:
- OUTPUT 1 (Y)
- INPUT 4 (G) – Left Turn Signal
- INPUT 5 (G/R) – Right Turn Signal
Can anyone shed some light on this for me?
Here are the relevant diagrams from the factory service manual (FSM):
BCS-3

LT-110

LT-111
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