Phase 1: Planning

On a stock Discovery I the fogs only come on with the headlights. When its REALLY foggy you want fogs to be aimed down low and cut underneath the fog you don't want your head lights on creating glare and scattering light in the fog making it harder to see. I realized on the way back from White Mountain in San Bernardino National Forest here in SoCal with a couple of friends last month in the pea soup fog bank we hit that this was a "feature" on the Discovery I didn't appreciate. On my Corrado I could run the fogs independently of the headlights which was the way it should be. Time to figure out how to do it on the Disco. After some good alone time with the rave electrical trouble shooting manual I managed to figure out what to change where. The good thing is that unlike the in the world of VW all of the headlights and fog lights are relayed from the factory in the Rover.. That makes making the wiring changes all that much easier. So first we have to track down where the fog light relay gets its power:



It gets its power from fuse F11 in the fascia fuse box(P126). F11 gets fed from the headlight switch. We cant change where F11 gets power from because it also supplies the headlights too. Hrmm.. lets see what else we can do.. How about pin 3 of connector C209 before the fog switch?



C209 looks pretty accessible since its right under the knee bolster foam next to the steering column. Sounds good, we can pull the wire from there. Here's what the connector looks like:



Now we have the wire, where are we going to get power from? well we want switched power, and we dont want to have to run a wire too far or have to run something that has a lot of load on it. Looking around at the wiring diagrams i figured something fed off of the accessory relay would be a good fit. Two circuits are fed from the accessory relay on the fascia fuse box F3 and F6, F3 feeds the radio and all the connectors are buried behind the dash and a pain in the butt to get to. F6 feeds the power seats.. Bingo, power seat relays are pretty easy to get to and have plenty of power to spare.



So we're going to add a bit of wire from the connector that we pulled from pin 3 of C209 and run it to terminal 86 of the power seat relay connector which is C358. Here's where it's located:



and here's where we will want to make our connection on C358:



doing this will allow us to turn on our fog lights any time our truck is turned on, not just with the headlights on.. more with the actual install

 

Nice!

 

The reason they are wired like that from the factory is that in most states, if not all, you're required to have your low beams on when the fogs are on.

 

Does this also bypass the High Beams? (i.e. the fogs turn off when the high-beams turn on).

 

*shakes fist at sky* goddam the man!! dont tell me what lights to have on when and where!! back when i used to have to walk uphill in the snow to and from school carrying all of my brothers and sisters since i had the only shoes in the family ramble ramble ramble..

Yes, since it takes the headlight switch out of the fog light circuit.

 

Nice write up. However, It seems like it would be easier to just wire an new circuit off the battery with its own relay and have it controlled by another switch.
Then you could always use the stock fog wiring and switch for some additional lights.

 

I shaved the bumper deleting the stock fogs and lower bumper fascia then added a set of hella 500 fogs using the stock fog wiring. The hella 500's, unlike the stock fogs, actually have a useful beam pattern. In the event i put the truck back to stock and sell it to some average joe schmoe I'll be able to reverse the modifications. fog light wiring drives fogs, easy peasy..

My roof rack lights will get their own relays and switches in a spare switch panel i picked up at the junk yard that took the place of the ashtray. But that's a whole other write up

 

I applaud you for doing the write ups. I always forget to take pics when I'm in the middle of a project.

 

That's what SWMBO (wife) is for.... unfortunately, mine loves taking pictures, but not of my 2nd love whilst in repair.