Rear Fog Wiring

[BuzzBomb]

Does anyone know if the wiring is in the harness in US cars to hook up the rear fog lamp? There is a two wire male pigtail that is unused under the left tail light- hopefully this is it but it isn't in the ETM. I suppose this means that I need the other end to be under the dash for the euro switch too(I need one of these if anyone has one..)

[Blue Shadow]

I installed the rear fogs/additional brake lights back in 87 and it required an additional wire from the fog switch to the rear of the car. I used a DPDT switch to make the change from fogs to brake lights. This was discussed in the Sept 1986 Roundel.

[BuzzBomb]

Anyone have a link to a Euro version of the ETM so I can see how this is meant to be wired?

[BuzzBomb]

Ok so the Euro version of the switch has a separate button for both the front and rear fogs, and ours have a single button. The question is, since the display above our single button has both the front and rear fog symbols, does this mean the single button has the connection to include the rear fog, but just not the wire in the harness?

[demetk]

Don't know if it's plug&play on the e28 but on the e23 it wasn't. Euro fog switch had the extra wire and position for the rear fogs but the US harness was missing this wire or I just couldn't find it. So I just used a unused speaker wire that was going to the old amp in the rear as the trigger wire to a new relay which powers the rear fogs. The rear fog indicator doesn't light up, but I guess I could get it to work by running a wire to the appropriate pin on the cluster.

I do like Blue Shadow's switch as a changeover from fogs to brake lights. Best of both worlds.

[Karl Grau]

I did it on my 533 years ago but since it used the early switch it was just a matter of running a wire to the trunk.

[MisterFixit]

I installed the rear fogs/additional brake lights back in 87 and it required an additional wire from the fog switch to the rear of the car. I used a DPDT switch to make the change from fogs to brake lights. This was discussed in the Sept 1986 Roundel.

... Euro fog switch had the extra wire and position for the rear fogs but the US harness was missing this wire or I just couldn't find it. So I just used a unused speaker wire that was going to the old amp in the rear as the trigger wire to a new relay which powers the rear fogs.

BlueShadow- Bravo, you are doing manually what I do automatically on Euro cars that have the rear fog wire.
demetk- It's not 'extra' on the Euros, it was deleted from US cars (semantics). From about 1975 forward, BMW left an 'unused opportunity' in the lights that would be a rear fog if it was a Euro car with a Euro harness. They get power from a (normally) grey/purple wire. Since it's not there, you run one with a switch (as Blue Shadow did) -- or find and re-purpose one (as you did).

I am building a set of lights for an E24 Euro shark right now that maintains normal Euro rear fog light function, and when the rear fogs are off it lights the same bulb as a second brake light. Like Blue Shadow, only automatic. With a relay, I get the bulbs to 'serve two masters', the best of both worlds.

Works the same with E21, E23, E24, E28, E30, E32, and others, I would think. Just needs a terminal set (in US cars), wiring, and a bulb to work.

Anyone interested in a setup for their car, get in touch with me and I'll build one for you as well. After testing to prove it works (I have a garage full of lights from the 70's forward), I'll make you an offer you can't refuse.

Of course, it is also possible to make the rear fog reflectors support THREE lights -- rear fog when you need them, brakes when you don't, tail whenever your lights are on -- using my high output 'Mo Brighta' 2-filament conversion bulbs. So Many Choices!

Vinceg101- I am testing this setup for you, too. Since you asked me like four months ago, I must apologise for the delay, but my E21 and E23 and E36 projects got in the way.

I will take/post pics of the E24 six series setup when it's done, with the correct color wiring (cut from a donor at the yard). The wiring is basically the same as an E28. Just a different lens and arrangement of the reflector assignments.

'Let there be Light!'

[Blue Shadow]

...when the rear fogs are off it lights the same bulb as a second brake light. Like Blue Shadow, only automatic. With a relay, I get the bulbs to 'serve two masters', the best of both worlds.

Interesting that your automatic feature requires one to turn off the rear fog lights and when done the bulb is repurposed as an additional brake light. This is similar to my manual system where I select whether the additional rear lamp is used as a brake light or a rear fog light with the dash switch. When I switch from rear fogs, the system automatically lights the additional rear lamps with the brake lights. I'm guessing the automatic part of your system is when the lights are off, meaning the fogs for the cars that can run fogs without the main lamps, then your system automatically uses the rear lamps for brake lights. Additionally, if the fogs are switched on and the lights are switched off meaning no lights on then the system would default to additional brake lights. If my system is in the fogs position and the lights are off, there are no additional brake lights. Maybe I need a relay.

Of course, it is also possible to make the rear fog reflectors support THREE lights -- rear fog when you need them, brakes when you don't, tail whenever your lights are on -- using my high output 'Mo Brighta' 2-filament conversion bulbs. So Many Choices! :?

I am not a fan of using a brake light brightness bulb for rear running lights. This gives folks behind you the impression you ride the brake and can lead to confusion when the brake lights are lit and they are no brighter than the tail lights. Others may be happy with this application of the additional lamp location in the US E28 rear cluster.

[MisterFixit]

I am not a fan of using a brake light brightness bulb for rear running lights. This gives folks behind you the impression you ride the brake and can lead to confusion when the brake lights are lit and they are no brighter than the tail lights. Others may be happy with this application of the additional lamp location in the US E28 rear cluster.

Nor am I - the third function is a tail -light -brightness bulb, just like the other tail light.

Others should be quite happy with this feature- this is the dual function upgrade for US cars that adds both tail and brake lights where the rear fog isn't ... if you get my meaning (my '+4' kit)

I am working on the E28 relay setup, will post separately, with a reference from this post, when it is ready for prime time.

Thanks!

[MisterFixit]

Does anyone know if the wiring is in the harness in US cars to hook up the rear fog lamp?

OK, you know by now, "not in US cars".

There is a two wire male pigtail that is unused under the left tail light- hopefully this is it but it isn't in the ETM.

I checked the US ETM, and found connector C405 meets your description. It is shown on page 5126-1 and -2, with the Central Locking diagrams. I recall you said the connector has red/brown and brown/yellow wires, which is exactly what is shown on these two pages, and matches what is is in my trunk under the left tail light. The other end of these two wires is at C404, in the bottom rear of the driver's door according to the connector chart.

The ETM says 'Not Used' for both of these connectors. It seems to be related to the 'Unlock Inhibit Request' which is described in the Owner's Handbook, page 2-03:

"By turning the driver's door key further to the right (clockwise) to a horizontal position, the central locking system activates an electromechanical locking system to further thwart theft."

I call it the 'Deadbolt' feature. When the driver's door lock is turned to the right past the normal locking position to 90 degrees (it requires some extra effort), you get a more secure locking of all doors. My 86 535i has this feature. It prevents the doors from being opened even if you gain access to the interior (BMW = Break My Window?) and try to open the doors by pulling up on the door buttons. They just won't budge. If you are going to try it, open all the windows first to test it.

The trunk also has a deadbolt feature. Using the master key you can turn the lock to the right to lock, then pull out the key in that position. The trunk stays locked even when you unlock the rest of the car from either front door.

My guess is that the connector is used in Euro cars to provide an additional point of access to this 'electromechanical locking system' feature from the trunk lock.

Anybody out there with a Euro car who can test this to confirm (or deny) that it has something to do with this system ???

[BuzzBomb]

I'd still like to get a EU wiring diagram so I can recreate the wiring for the fog light circuit. My original one button switch has 2 wires, and my two button has 4 wires. I tried to just plug the two button in to the original socket, but it didn't do anything, so the wiring is completely different. Doesn't anyone outside of the US have a schematic?

[MisterFixit]

I'd still like to get a EU wiring diagram so I can recreate the wiring for the fog light circuit. My original one button switch has 2 wires, and my two button has 4 wires. I tried to just plug the two button in to the original socket, but it didn't do anything, so the wiring is completely different. Doesn't anyone outside of the US have a schematic?

I think we can figure this out without killing too many brain cells, don't you? Let's attack it logically.

1) Is there a set of wires connecting to the fog light switch in your car- what are the colors and relative diameters (are they 'signal' or 'power' wires)?

2) Do you have access to the US ETM (wiring diagrams) for your car?

3) Are you willing / able to run a wire back to the rear lights?

4) Do you want some help sorting this all out? email me, we'll have a go at it. I have many of the parts and wires to get this done on hand, cut from US and Euro harnesses over the years, just waiting for a new home and a new purpose in life.

Andy

[BuzzBomb]

Thanks for your help.
1- yes, two. They are the ones shown in the etm.
2- yes
3- yes
4- sure, I'll pm you, but do you think other people would benefit from the retrofit steps? Either way let's do this!

[MisterFixit]

Thanks for your help.
Q1- Is there a set of wires connecting to the fog light switch in your car ...
1- yes, two. They are the ones shown in the etm.

OK, I assume you mean the yellow/white and grey wires. They are control: yellow/white is 'hot' from headlight switch, grey feeds the relay coil to switch on the fog lights, but only when the low beams are on. When you go to high beam, the fogs and lows go off (more on this below).

Q2- Do you have access to the US ETM ...
2- yes

I found this switch on pg. 6312-0, in the 533i/ 535i ETM (for my 1985), under HEADLIGHTS/FOG LIGHTS CONTROL.

Q3- Are you willing / able to run a wire back to the rear lights?
3- yes

OK, I suggest tapping fuse 15. The wires on the switch are thin to supply power. They just switch relays on and off, no real current there. BMW uses a minimum 1.0 wire, and the majority to the rear lights is 1.5 mm(2). I would go 16 AWG minimum, 14 would be better. The thicker, the brighter.

Q4- Do you want some help sorting this all out? ...
4- sure, I'll pm you, but do you think other people would benefit from the retrofit steps? Either way let's do this!

I will get a tape measure and try to follow the existing harness to get a length for the feed wire. I have plenty of terminals, and can solder on the ones to make it fit into the existing tail light connectors in back.

While you're in there, there's a method to defeat the relay back-feed that kills fogs and low beams with 'High Beam ON', by the way. Useful for Hella BiFocus, Cibie CSR, and other European H1 Low Beam headlights. Has to do with that white/red wire between the high, low, and fog light relays. Optional of course.

With this method, the fogs light regardless of headlight hi/lo switch position - nice if you have auxilliary driving lights wired to the fog light circuit, for example.

Andy

[BuzzBomb]

I appreciate the help. Honestly though, I'm kind of flabbergasted that out of all the e28 owners outside of the US, nobody can scan or forward one page out of the schematic that would answer this question about the two button fog light switch, and save us from planning a workable solution to the original wiring of non US cars. Is it a big secret? Crazy. Sad thing is, here in desert southern CA, I can't remember the last time there was fog, so this really is not a necessary addition to my car. I just like punishment, I guess.

[BuzzBomb]

Thanks for your help.
Q1- Is there a set of wires connecting to the fog light switch in your car ...
1- yes, two. They are the ones shown in the etm.

OK, I assume you mean the yellow/white and grey wires. They are control: yellow/white is 'hot' from headlight switch, grey feeds the relay coil to switch on the fog lights, but only when the low beams are on. When you go to high beam, the fogs and lows go off (more on this below).

Q2- Do you have access to the US ETM ...
2- yes

I found this switch on pg. 6312-0, in the 533i/ 535i ETM (for my 1985), under HEADLIGHTS/FOG LIGHTS CONTROL.

Q3- Are you willing / able to run a wire back to the rear lights?
3- yes

OK, I suggest tapping fuse 15. The wires on the switch are thin to supply power. They just switch relays on and off, no real current there. BMW uses a minimum 1.0 wire, and the majority to the rear lights is 1.5 mm(2). I would go 16 AWG minimum, 14 would be better. The thicker, the brighter.

Q4- Do you want some help sorting this all out? ...
4- sure, I'll pm you, but do you think other people would benefit from the retrofit steps? Either way let's do this!

I will get a tape measure and try to follow the existing harness to get a length for the feed wire. I have plenty of terminals, and can solder on the ones to make it fit into the existing tail light connectors in back.

While you're in there, there's a method to defeat the relay back-feed that kills fogs and low beams with 'High Beam ON', by the way. Useful for Hella BiFocus, Cibie CSR, and other European H1 Low Beam headlights. Has to do with that white/red wire between the high, low, and fog light relays. Optional of course.

With this method, the fogs light regardless of headlight hi/lo switch position - nice if you have auxilliary driving lights wired to the fog light circuit, for example.

Andy

So the original one button pigtail has two wires, and the two button pigtail has four. Plugging the two button switch into the original pigtail doesn't work no matter what combination of buttons you push so the switch is completely different from the one button switch, schematically. I'd rather not pull the switch apart to break down the schematics, but since it's such a dearly kept secret, I might have to. I suppose the one button switch would be easier to keep and just run a wire to trigger the rear fog when the button is pressed would be the easy route.
Hell no! I'm fully involved, now. Gestapo code breaker in full effect. This pointless rear fog light that I'll never use will be working, and soon.

[Blue Shadow]

This pointless rear fog light that I'll never use will be working, and soon. :|

That is what we needed to hear. Get after it and let us know.

The two button switch is just two on/off switches. The key to using them is the wiring, not the switch. I use one to turn off the power to the antenna so it will not deploy when not using the radio and to turn on amp cooling fans. I use these as needed.

[MisterFixit]

Hello again, I promised to update this post when the system I designed was "Ready for Prime Time."

I guess I missed it, but the question comes up all the time now, so I thought it would make sense to explain.

I have developed and built a lighting system that does very nicely with rear lights in Euro and US cars.
It includes relays to 'take the load' of additional lamps off of the stock circuit (fuse, switch, wiring, etc.).
An optional relay kit allows the check panel to operate normally under normal loads for brake and tail lights.

US cars, it adds a second tail and second brake light inside the existing sockets. The relay option supplies power that is tapped from your power antenna circuit - without cutting any wires.

I can add single or dual rear fogs in US cars if you want, to work as you like - independently, or as described below under 'Euro cars.'

Euro cars with working rear fogs, it adds a second tail light and second brake light (both at appropriate brightness) PLUS allows the rear fog light to function normally. If you turn ON the rear fogs, they come on normally. If you turn them OFF, the bulbs are tied in with the brake circuit to work as additional brake lights. Tail lights are normal (dim) brightness, no surprises there. And the best part - it all works automatically with relays, and without cutting any wires. No switches other than the stock brake and fog light switches that came with the car.

All kits I do are removable, so if you don't like the changes, you un-install the kit, and you're back to normal stock wiring.
All kits use high output nickel base (silver color) bulbs, as required.
NO kit will ever melt a lens in your tail lights unless you put a brake light bulb in a tail light socket. That's been done, we know what happens, it's not pretty.

This is just a sampling of what I have developed in the Laboratory, there are lots more options to "Be Seen and Not Hurt."

[MisterFixit]

Bump-ity Boo.

Current projects under way-
E12 M535i (Euro car) - getting the dual tail, dual brake, plus working rear fog lights. This car came with only one rear fog, driver side (left), so I am adding a second rear fog light on the other side, along with relays and upgrades for the double tails and brakes.

Improved design for 2002 round tails - small harness connects the internal wiring for the dual tail light upgrade. Makes the kit easier to connect, and easier to uninstall (if desired).

New lamp testing - Philips has a new design for LED replacement lamps to fit BA15S sockets (standard tail lamps) that claims to mimic the light distribution and radiation of a filament lamp. I will be testing 85 cp red and 350 cp white versions of this new design.

'Keep those cards and letters coming, folks!'

[tig]

Some useful (I think) related info here: viewtopic.php?t=155587