You can also ground the yellow wire right at the headlight, to save the hassle of taking off the whole electric box. This picture isn't mine, I got it from this thread: Headlight All On Mod - Page 8 - Chevy and GMC Duramax Diesel Forum
Lots of info on this mod.

 

Has anyone with a 2001 or 2002 figured out how to make the fog lights stay on with the high beams yet?

 

Run a diode from the HDLP relay, 85 pin, to the FOG relay, 85 pin, in the electric box under the hood. This should keep the fogs on all the time, high and low. I'm not sure how you would do it with just the high beams, if thats what you mean.

 

That method only works on the 2003 and up trucks.

I still have not found any info on how to do this with the 2001-2002 Silverado's.

Any other ideas?

 

I haven't tried this, so I'm not positive it will work but it makes sense. If you ground the negative wire to the fogs, to the body somewhere, similar to the yellow wire that you ground on the low-beam. Then splice the power wire from the fog lights to the power wire from the low beams, this would send power to the fogs whenever there is power to the low-beams, and with the fogs always grounded, they would stay on whenever the lows are on. And if you did the hi/low mod, they would be on all the time. I think

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Don't mind my drawing, I just drew it up real quick. But I was thinking something like this. I don't know why it wouldn't work?

 

I think that would work, but you would not be able to turn the fogs off when you have the low beams on.
You would not be able to run the fog lights by themselves either...Right?

 

Here is how its done on the 03+ models. you use a diode

 

I never thought about turning them off or using them by themselves, was just thinking about having them on with the headlights. I think by leaving the fog light power wire hooked to the factory switch, and running a jumper wire with a diode from the low-beam to the fog light power, you could turn them on by themselves, without the headlights. Then the only issue would be turning them off while you have the headlights on.

Edit: Added the Yellow wire. You may be able to run a wire from the diode wire, to a switch in the cab, to have the ability to cut power to the fogs with the headlights on. This seems like its a little complicated to me, but as far as I know jumping the relays with a diode wont work on the 00-02? There may be an easier way but this is what i came up with.

 

that diode would burn up if you hooked it up like that, jump the signal wires with the diodes, not the full current

 

K, wasn't sure about that. There's gotta be an easier way to do it on the 00-02s