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How To: Low/Fog and Low/High/Fog question

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Old Apr 6, 2014 | 07:35 AM
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Default How To: Low/Fog and Low/High/Fog question

From the factory, the highs and lows come on when you hit the brights. However, my question is, can you run a Diode from the Low relay to the fog light relay(under the hood like you can on the GMT800s when making the 3 way high beam) and achieve the following: 1) Fogs will come on automatically when the lows beams come on. 2) Fogs will stay on when high beams are selected. and 3) Fogs will be able to be turned on without low/high beams?

Basically, I would like to bypass the switch so they turn out automatically at night with the low beam and because I have HIDs in the Fogs, keep them on with the high beams so they don't have to be cut on and off switching back and forth.

Thanks!
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Old Apr 6, 2014 | 07:59 AM
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I'd like to know this as well. Having to switch the fogs on and off is annoying
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Old Apr 6, 2014 | 09:52 AM
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im not sure about the fog lights coming on automatically with the low beams. but i use the 6 hi mod, which cuts all the lights on (low, high, fogs) when you flip the high beam switch its a simple mod. takes 1 relay and about 5-10mins. heres a link:

HOW TO: NNBS 6-Hi mod (the proper way) - Chevy Truck Forum | GMC Truck Forum - GmFullsize.com
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Old Apr 6, 2014 | 10:23 AM
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Nice... i know what im gonna be doin later this week
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Old Apr 6, 2014 | 10:32 AM
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Originally Posted by Jason Z69
Nice... i know what im gonna be doin later this week
I think I might have to do the same haha
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Old Apr 6, 2014 | 11:40 AM
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Well, if the low beam is on and you flip the switch to the high beams then the lows will still be on thus the fogs will still be on is my thinking. The question becomes...how to make it work. I think just running a diode to the fog light relay in the fuse box may work but don't know and need some clarification.
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Old Apr 6, 2014 | 05:51 PM
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you will prob need about 2 relays for this I'm thinking... One to take signal form the low beam relay and one to take signal from the high beam relay. The factory switch will give you your power when neither low or high are being used.


Relay one

85: Signal wire from Low beam
86: Ground
30: Positive
87: Connect to signal side of factory Fog Light relay

Relay Two

85: Signal wire from High beam
86: Ground
30: Power
87: Connect to signal side of factory Fog Light relay

Last edited by Three6GMC; Apr 6, 2014 at 05:59 PM.
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Old Apr 6, 2014 | 07:56 PM
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Glad ya brought this up ! I need to do it also ,

I really really really want to make my front amber parking lights my DRLs , that would look so sick , I hate headlight drls they look like **** .
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Old Apr 6, 2014 | 08:38 PM
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It can be done under the dash with a diode. Jump the low trigger to the fog light trigger at the bcm. Search for it. I found it on here and did mine last year.

Found it

https://www.performancetrucks.net/forums/showthread.php?t=502129

Last edited by Truckshop; Apr 6, 2014 at 08:43 PM.
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Old Apr 6, 2014 | 09:20 PM
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Pink/white wire from the brown connector hooked to the green/white wire on the black connector on with a diode. Both connectors side by side on the bcm. Will make the fogs stay on with the lows. Stripped side of the diode to the pink/white wire.

I know this is old but its the best info I could find when trying to hook mine up yesterday.

This is what you posted TruckShop....green/white is fogs and pink/white is low beam?
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