I just finished installing fog lights on my truck and all I have left to do is wire in the positive signal wire from the relay (#86). Obviously I could just do a regular switch but I would rather tap it directly into the low beams so they automatically come on with the headlights. Anyone know the best place to tap into the low beams on an 09? I'd like to do it somewhere right off the headlight switch but without pulling the whole dash apart how would I find the correct wire? Any thoughts or ideas?

 

You don't want head lights on, low or high beam, when you use Fog Lights.

Point of Fog Lights is to be well under drivers line of sight and hopefully under most of the fog so reflected light is minimized.
If your low beams are on then benefits of fog lights are lost in the reflected light from the higher up lights

Head lights are controlled via the Smart Junction box in the cab so easiest place to get low beam power will be at the head lights themselves
Low beam wires are:
Grey wire on Right head light
Violet wire on Left

The violet/orange stripe wire is High Beam power for both

Relay draws about .3amps so won't effect either low beam or there separate fuses
Each low beam has a separate fuse in cab, #3 and #4 10amp

So just use a wire splicer(used for trailer lights) into either low beam wire.


And just as a heads up.
If you do want to use a switch, IMO better, then you would use GROUND(#85) on relay
get relay power on #86, key on or key off power, your choice
Then you run just the 1 GROUND wire from #85 into the cab to a switch and wire switch with local cab GROUND.
Thats what all automakers do, better to use GROUND as activator, less wiring and less 12volt wires to short out

 

Thanks so much for the quick response. I guess I'll just go ahead and use a switch. One quick question with using the switch to activate the relay ground (#85). Would I then simply tie the relay signal positive (#86) directly into the relay battery power line (#30)? And if so should I run separate fuses for #30 and number 86?

 

Yes, you can just use a jumper wire from 30 to 86, but then it would have power all the time so you could accidentally leave fog lights on and drain the battery, up to you

No, if you use the jumper no extra fuse is needed, as long as #30 wire is fused
But you could use an in-line 5amp fuse as the jumper between 30 and 86, not to expensive

There are Key On fuses in the engine fuse box that could be used to power relay's 86 so no power when key is off

 

Well this is what I ended up doing. Since I mounted the relay right next to the battery I just ran #86 and #30 direct to the battery (fused seperately) #30 has a 20 amp and #86 has a 3 amp. Then ran 85 into the cab to the switch with the other end going to ground. I really like the idea of no positive wires running into the cab. Thanks for that idea.

I want the fog lights to be able to go on without the truck running so I'm not worried about hooking them to an ignition only power source. I'm sure I will forget them and kill my battery at least once though...

 

Good work