OK, first off, I actually did do quite a bit of searching through the forum, and found lots of info referring to this, but no actual instructions on how to do it. (at least as a stand alone mod)
Also, I DO realize it is technically illegal, but don't frankly care.

I just want my fogs to stay on when I engage my high beams.
I still want to use the headlight switch to turn them on/off as stock. (as opposed to wiring the fogs into a separate dedicated switch)
Is there a simple way to bypass the fog light cancellation when the highs are on?
Preferably without disassembling the column or dash?

 

No guarantees, but in this case, there are 2 possible solutions that come to mind :
1. use a SPDT relay energized by the hi-beam circuit to supply 12v to the fogs from the NO contact, when not energized, the NC contact wired to the standard fog 12v connects to the fog common.
( SPDT = Single Pole, Double Throw , NC = Normally Closed, NO = Normally Open )
WIRING :
relay common to fog lights 12v
relay NO to fused battery 12v
relay NC to fog supply 12v
relay energize to high-beam 12v
relay ground to ground
MAKE SURE THE RELAY CAN HANDLE THE VOLTAGE AND THE AMPERAGE AND USE WIRE AT LEAST THE SAME GAUGE OR BIGGER !!!

2. Use a honkin big diode on to do the same thing, however the 12v to the fogs would be pulled from the hi-beam 12v, probably too much for the fuse.

So, in summary, I'd go with the relay. ( might be a slight flicker as the 12v is removed from the fogs when switching to high before the relay closes. )

 

I appreciate the info. I think I understand the concept, but I'll admit, wiring is not my forte.
So is the function of cancelling the fog lights integrated into the switch?
Sorry to be dense, just trying to understand how the system works. Please forgive my ignorance
So the relay would send 12v to the fogs instead of an open circuit? (right?) Can that "switching" of voltage sources be avoided?
Ie: the fog lights are already receiving power, then the highs are activated and power is removed from the fogs, then the relay kicks the voltage back on. (with the modification you mentioned)
I guess what I'm asking is is it possible to just bypass that function altogether so that power to the fogs is never interrupted, or would overriding it via a relay as you mentioned be necessary?

Thanks! I appreciate the info, even if my grasp of it is tenuous.

 

As the power to the fogs is controlled electronically by the LCM ( Lighting Control Module ), you would have to rewire something in the dash, which would then invalidate the switch function, something you want to avoid.

When you switch to high, the power to the fogs is disrupted, you have to replace that power with another source of power, hence the relay. If you are a real electronics guru, or can find a solid state 12v SPDT replacement for a relay in Google ( kinda hard to find with enough amperage to do the joib ) - this would eliminate the approx 2-20 millisec delay

see this link for a relay primer :

Relays


NOTE: I used the bosch 30amp relay 10 years ago on my old 1990 Suburban to make the low beams stay on when you switched to high. Still working fine ...

ANOTHER NOTE : IF YOU USE THE RELAY AS DESCRIBED ABOVE, THE FOGS WILL BE ON WITH THE HIGH BEAMS REGARDLESS OF THE FOG SWITCH POSITION !!!

 

Thanks so much for the clarification. The info about the LCM is what I was wondering. And tampering with it is something I would want to avoid.
I always run my fogs whenever I'm using the headlights, so the always on with the high beams is not a concern, I just didn't want to install some ugly aftermarket switch to accomplish this. I rarely need the use of my high beams, but hate the loss of foreground lighting when I do need them.
Your solution sounds like just what I want.

Thanks again!

 

If you can find a shop near you that does car Alarm installations they should have NO TROUBLE making this work, especially if you supply the pinout to them that Alaxfire gave you.

Just make sure they use a 5 pin relay, not a 4, you NEED to ensure you aren't just adding 12V to the fog line but actually disconnecting the original fog output from the switch when it is energized otherwise you may damage the Bulb Out indicator system built into the headlight switch module.

 

Very good to know, Thanks!
I don't want to damage any existing systems.

 

Just a bit of trivia, but here in Australia the fogs don't automatically turn off when you use high beam, must be different rules over here. Cheers James