I really don't know their correct name, but I am interested in having the lower fog lights come on automatically either every time my headlights come on (without me having to push the button to turn them on) or on all the time when the engine is running like DRL's. Either would be ok with me. Is it a simple change out of the relay with a different type of relay, or cutting and splicing a wire that feeds the relay that turns these on? I searched and didn't find where anyone has done this already. Any thoughts?

 

Drivers Handbook warns front Fog Lights should not be used with the headlamp main beam (high beam) which means wiring them to go off again with high beam.

There must be a reason this warning is repeated for all model years but the Handbook gives no further explanation.

You could upset a lot of oncoming drivers and those you are following with your Fog Lights permanently on in clear visibility.

Graham

 

Thanks Graham, good point. I don't know if the UK configuration is the same, but on my car, when I press the button to turn on these lights, they automatically shut off when the high beams are on, and the on again when back to low beams. I guess I don't really want to upset that function, although I can't understand why they can't be on with the high beams (unless it is too much current draw). But since the factory configuration is for them to be on with the low beams, I don't see how this can be an issue for on-coming drivers in either case.

 

Disclaimer: I've never tried this and am just speculating

From the schematic:
Exterior_light.pdf

It looks like you could probably do it a could of ways.

1) if DRLs are what you want, you could likely find someone to enable the function in the body processor and they would behave in the standard way.

2) you could tie pull power for the fog light off of the headlight power, which might pop the fuse since the fog light is 15A by itself and the dip beam only 10A

3) you could jump the fog light relay switching signal to the dip beam relay switching signal, connecting LF5-7 to LF5-8. These relays should be rather near each other in the engine bay fuse box. This is probably the safest and easiest since all of the loads stay on their respective circuits and you are only doubling up on the switching current. It would probably be good to check the actual current draw of the relay just to be sure you aren't doing something bad to the body processor since it will be carrying the headlamp and fog lamp switch current on the same channel.

 

Iwas thinking of something along the lines of #3. In #1, I don't want the headlights on as DRL's, which is what that programming does I think. I prefer to just have the fog lights on when ever the low beams are on (or whenever low and high beams are on if possible), but an acceptable option would be for fog lights whenever car is running. I think I like #3 best, but I am concerned with how, if at all, that might cause an electical issue upstream to the actual push button switch on the dash. I doubt it would be an issue, but want to be sure.

 

You could always just try it and see if the magic smoke leaks out.

The body processor is pulling the switching line to ground when the lights or fogs are turned on, so I don't think it's going cause you any problems.

The odd behavior you will see is that turning on the fog lights will also turn on the headlights. But that's what you are going for anyway so the "problem" is limited to a confused next owner.

If you really wanted to prevent this, you could probably use a diode between the two to make sure current only flowed from the fog to the headlight line and not the other way.

 

Just my 2c on the fog lights and high beams that I learned years back whe I still had a BMW 528 E12 body!

Fog lights are used in fog, where high beams are useless. If you can use the high beams, you do not really need fog lights. The fog lights installed are typically low on the car, since there is less fog on the first 12 inches than at driver's eye height. Some countries have laws that prohibit the use of three sets of lights switched on the front of a car at the same time. Since may people (I did the same years back) drove at night with the fog light turned on in no fog to illuminate more road, using the high beams would switch off the fog lights.