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move drl from headlight to fog

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=135055
Printed Date: May 01, 2025 at 4:27 PM


Topic: move drl from headlight to fog

Posted By: sse1990
Subject: move drl from headlight to fog
Date Posted: October 12, 2013 at 12:35 PM

I've got a 2012 GMC sierra that uses the low beams as DRL. There is a signal wire from the BCM (LT GREEN/ blk) that runs to the DRL PCB Relay, that is connected to the lows. My fogs have a signal wire from the BCM (DK GRN/WHT) to the fog relay.

What's the best way to move the signal wire from the DRL relay to the fog relay and still maintain the factory fog signal wire.

I was thinking of adding diodes to prevent the BCM DRL signal from going back into the BCM fog signal and vice versa, but is it needed since they are negative BCM signals?

I've seen other ways by adding a relay after the DRL relay and converting the output of the second relay to negative to trigger the fog relay, but that starts to look crappy when you open the fuse box.



Replies:

Posted By: powerslave
Date Posted: October 18, 2013 at 12:49 PM
I know you said using a relay it looks CRAPPY in the fuse box, but that is the way to do it.. Actually, it's just one jumper wire to the FOG relay in all actuality.

You only need to run a jumper from the coil input side of the DRL relay, to the coil input side of the FOG relay, with a DIODE in the jumper.

DRL ---->|---- FOG





Posted By: powerslave
Date Posted: October 18, 2013 at 12:50 PM
Can't edit my post, so:

The DIODE will prevent current going back to the DRL relay when the FOG lamps are on manually; thus it won't trigger the DRL relay too.





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