concor

I have a 928s '84 euro.

Got a little problem. When I turn on the normal lights, the rear fog light stays on continually. Using the fog switches doesn't get it off. It is strange because the rear fog light shouldn't even be able to get on before the front fog lights are switched on. Anyone any ideas? I have to get working for the dutch variant of the MOT.

I wish I discovered it earlier because I just took out the instrument pod and the CE panel for a good cleansing.

concor

I removed the two fog switches from the pod. The rear fog light is still on That wasn't it...

Leon Speed

Edit: I tried to read the electrical diagram, but can't seem to make out how the light is powered. The fog relay seems to power the front fog lights only.

Mrmerlin

more than likely is you have the fog lamp plugged into the tag lights you may have to remove the rear bumper cover to sort this out,
unless you can work from under the car.
The foglamp and tag wires should all be in a smaller harness with three bullet type connectors and they run along the top edge of the bumper support bar
( the heavy metal under the bumper cover) the wires may be clipped to the rear portion of the chassis

concor

@mrmerlin, always nice to see you here! I believe the problem is in the pod or the ce panel as the problem appeared after I worked on those. I haven't been at work at the rear bumper.

concor

Hmm, nobody? I searched again but there is no thread on this problem. Really hard problem.

Landseer

Well, get the wiring diagrams, voltmeter and start tracing.
That's what I'm doing here every other day it seems.
Its actually amusing.

Mrmerlin

After I fixed?????? the rear foglamps is on.

OK so now you know where you have to look,

NOTE You probably have one of the connectors on the wrong switch

concor

Thank you for the tips. Really appreciate it.

@Landseer. Yes, I think I have to learn to read the schematics and how to test them. I have some basic electric skills as I managed to track down the battery power leaks with millliamps and all. From 250mA to 30mA to be exact. And managed to fix my ignition wires, one was 6 kOhm which should have been 3 kOhm. So I should be able to learn how to track this down too.

@mrmerlin. I just had a look. I pulled the two switches for the front fog and the rear fog light and noticed that I wrote on the switches and connectors 2L and 3L which stands for 2nd and 3rd from the top Left side. Unfortunately they were connected correctly.

I removed both switches as a test and the rear fog light is still on

Anyway, I am caught in three 928 projects and it is driving me a little crazy. I discovered that vehicles before 1999 don't have to have a rear fog light for the MOT. So I am putting this one on the long run and pull the bulb for now. I'll get back to this thread, thanks again for the advice.

Mrmerlin

If you can post pictures of the work you did and the parts you touched it may be as easy as swapping a connector

Landseer

Stuck foglight relay?

concor

Well, this is fun.

Relay XII is the wrong relay! It is a simple relay with 4 connections like the window regulator relay. It should have 6 connections! Relay XII does tick when we push the front or rear fog switch.

Both the fog light switches (front and rear) enable the front fog lights.

The rear fog light is on with:
- Relay XII removed
- Fuse 34 (rear fog lights) removed
- Front and rear fog light switches removed
- Normal light switch in the on-position (side markers and low beams)

Landseer

Well, looks like you've got some real tracing to do.

The 83 diagrams might help you because they have wire colors and are almost the same as 84 diagrams on these body / light accessories.

Why don't you pull the pod, take some great photos that include wire color, and let some of us compare.

Did foglights always work differently for you or are you just noticing this.

What market was your car sold into originally?

(there are some alternative setups for rear fog IIRC)

Bart-Jan

I had a similar problem on also a Dutch car with the same issue right before the 'APK'... However with my car, a '85 Euro S, it would never switch on. It turned out everything in and around the fog light has lived in years of dust, salt and water, which isn't the best climate for electrics. I advise to start tracing the wires from the light going back to the switch. Probably somehwere you have the same issue as mine, or another issue I had with the rear harch release: two wires were bare because of continues abrasion (slijtage) and made a shortcut.

Leon Speed

If I'm reading the wiring diagram correctly the relay powers the front fog lights only. Second, pulling the fuse doesn't change the symptoms, is consistent with the wiring diagram, since it shows the rear fog lights are powered through the fog switch and then through the fuse. There is nothing between the fuse and the rear fog lights but wire.

That means either you inadvertently misrouted some wiring at the CE
or the rear fog lights are plugged in incorrectly.