Need rear fog light help.

[JonM]

So I have the whole interior out at the moment. Great.

The walnut driver's side dash pod came with a different switch blank than what I had on my black vinyl pod. On the left side of the steering wheel, the stock pod had a switch blank with the RDC tire pressure monitor icon. The walnut pod (stock on Z3 extended leather coupes) obviously does not have a RDC icon since RDC is N/A on Z3 coupes. Instead, the walnut pod has a switch blank with icons for both front and rear fog lights.

So I've started thinking about adding a rear fog light. That in itself is pretty straightforward, albeit a pain in the ass. But whatever, I've gone this far. Then I start looking at the instrument cluster. There is a spot for a rear fog light on indicator. Cool.

My question of this whole post is: Do I need to use a relay?

I am tempted to tap into switched power, run switched power through a rear fog light switch (I think I found a dual RDC/rear fog switch in EPC... I ordered it to see what it's like), to the idicator on the dash via pin whatever (same procedure used when I added fog lights to my 318ti) and then finally back to the rear fog light bulb. This means hot power is travelling all over the car.

I'm still not sure what to do about the front fog light icon. I don't know how I can salvage the RDC icon from my stock pod.

[Randy Forbes]

Jon,

whether or not you "need" a relay depends on the current draw of the lamp and the contact rating of the switch.

The switch will certainly last longer if its only work is to pull in the coil of a relay. When you put the inrush current of the lamp (basically a short) through the switch every time you turn it on, the switch's contacts will eventually burn up.

Considering all the pains you're already taking with your car, my suggestion would be to use the relay and never have to look back.

[JonM]

Originally posted by Randy Forbes
Considering all the pains you're already taking with your car, my suggestion would be to use the relay and never have to look back.

Peace. I agree. Then the question is, what relay do I use for this and where do I mount it.

I'm hoping Ron will chime in here...

[Ox///M]

You can use a simple Compact 1-Amp SPST Reed Relay-12VDC, or a SPDT N.O. Automotive Electro-Mechanical Relay 12V-Coil Contact Rating: 20A@14VDC (copy and paste from radioshack.com)

Mounting, see Ron. I usually just buy a small project box ($1) from RS and then mount it somewhere.. I'd put it in the back near the rear fog light, as there is plenty of room back there.

[Ron Stygar]

Pic shows the E36 dual fog light switch. I modified the left hand switch (easy) to be momentary for the tire pressure function. Uses the same four pin connector except you have to move the current pins to the other two positions and add the rear fog pins where they were. Will post more on this later.

<img src="http://www.unofficialbmw.com/images/dualfogswitch.jpg">

[JonM]

Ron, thanks. I will order one.

This is what came with the pod:

http://www.leatherz.com/pics/coupes/lz1/fogicons.jpg

[Ox///M]

Jon,

Is that yellow leather or tan? Isn't your coupe Imola?

:confused:

[Ron Stygar]

BMW doesn't use a relay for rear fogs. Just over 3 amperes for the two rear fog lamps. You have to create positions for these in the rear lamp assemblies. Punch out the plastic and add contacts or simply solder to the new lamp assemblies once you remove the plastic. While your at it you might as well double up the brake lights too using a couple of diodes that can handle the current of each lamp. You have to run one wire from the front switch to the back along the left side.
(I like this edit option)

<img src="http://www.unofficialbmw.com/images/brkfog1.jpg">

<img src="http://www.unofficialbmw.com/images/brkfog2.jpg">

<img src="http://www.unofficialbmw.com/images/brkfog3.jpg">

[Randy Forbes]

Now you're with it!
Way to go Ron!

[JonM]

Walnut looks yellow under heavy flourescents and with the flash.

This is more accurate:

http://www.leatherz.com/pics/coupes/11.jpg

[DaveM]

hey you BMW guys that have done this (Jon, RS)

How exactly did you switch out the fog light switch?

Was it the same size?
Anything special about taking it out?

thanks!

dave

[acao]

Hey Jon,

How well do the panels fit together now that they are covered by an additional layer of leather? It seems like in some spots, it would be a tight squeeze.

[JonM]

Originally posted by acao
Hey Jon,

How well do the panels fit together now that they are covered by an additional layer of leather? It seems like in some spots, it would be a tight squeeze.

They all fit fine. Without the vinyl, the difference on pod dimensions for example, is nill.