Strange fog light problems

[drdan]

Dear All,

I'm mighty confused. I had a play with my new multimeter last night trying to trace two separate but maybe related faults in my fog light system. Firstly, my rear foglight (underslung cheapo type) does not light. Secondly, front spots, although wired do not work. MOT due in a month or two so need to sort them out.

Here's what I found.....

Symptoms:

Main fog switch on centre console below transmission lever; when switched (with sidelights/headlights on) causes FOG fuse (15 A) to blow in driver's footwell fusebox.

The rear foglight bulb is fine and the wiring looks unfrayed. I traced it up through the rear floor, under the carpet and alongside the drivers side. I checked the foglight switch in the centre panel and it is behaving as it should, ie simply breaks or completes a circuit. I checked the voltage at the switch wires and it reads 13.7 V (with headlights on) and 0 V (lights off). Is it normal that the voltage is higher than 12V? I checked both batteries and both show 13.2 V. Could this cause an overload, enough to blow a 15A fuse? Surely, 15 A is a lot? Is it likely to be a fray that I have missed somewhere or can anyone think of a more likely explanation?

There is a separate switch fitted in the dash under the steering column/ignition that has two positions, on & off (obvious I know). When sidelights/headlights are on this switch will light up in ON position and switch off again when I change to fullbeams. From this I deduce (based on many useful threads in this lovely forum!!!) that it is probably for the front spots and is wired (correctly) through the headlight wiring to behave as above. The problem is that despite what the illuminated switch says there is no activity in the front spots, no light.

I have checked the wiring at the spots. Both are wired together in parallel and have two supply wires coming in from somewhere behind the battery. These read a constant 0 volts irrespective of the internal switch's position so I guess the power is not reaching that point on the back of the nudge bar. No problems with the headlights/sidelights/indicators/full beam etc.., just the spots. Could there be another fuse somewhere hidden behind the dash or elsewhere?

Any help or advice would be much appreciated? I am a newbie to Surfs, rapidly falling in love (OK fallen already!) and am keen to learn how to tinker with her underbody (so to speak!).

Cheers,

Dan

[BUSHWHACKER]

The illuminated switch on the dash is normally the rear foglight that illuminates to tell you that the foglight is on. foglights go off when highbeam is activated. The switch in the centre consol is most likely for the front spots that usually come on with the high beam.

Also, the front spots should be powered with seperate fuses and relays.

[Taliesins]

For the MOT the rear foglight must operate while normal lights are in the dipped beam position. It can come on at any time as long as it operates whilst in the dipped beam position and can be switched on and off from the normal driving position. Front fogs/spots are not part of the MOT.

Check the earth on the rear fog.

On the front lights the wires will probably be one supply one earth, if you cant trace the problem rewire using the switches you have, this will solve the problem.

[drdan]

Thanks guys.

Bushwhacker: If the fuse blows when the centre console switch is pressed does that imply the fault is with the front spots or their wiring then? I thought that the fuse for FOG in the footwell would be for the rear fog? Do you think both front and rear are somehow wired together?

The illuminated switch is located in the recess below the ignition switch and is a red plastic switch, not of the same black plastic rocker switch type that comes as standard. Do you reckon that could be a later fitting after import?

I may have to just rewire the whole system as Taliesins suggests but I'm new to this game and a little hesitant to tinker too much with completely new wiring. I'm alright at looking for frays and such and checking voltages/resistances but I'm trying to walk before I run.

I'll take another look this weekend. Wish me luck!

[Taliesins]

Thanks guys.

Bushwhacker: If the fuse blows when the centre console switch is pressed does that imply the fault is with the front spots or their wiring then? I thought that the fuse for FOG in the footwell would be for the rear fog? Do you think both front and rear are somehow wired together?

The illuminated switch is located in the recess below the ignition switch and is a red plastic switch, not of the same black plastic rocker switch type that comes as standard. Do you reckon that could be a later fitting after import?

I may have to just rewire the whole system as Taliesins suggests but I'm new to this game and a little hesitant to tinker too much with completely new wiring. I'm alright at looking for frays and such and checking voltages/resistances but I'm trying to walk before I run.

I'll take another look this weekend. Wish me luck!

I would say (if its like mine) that the switch below the ignition switch is for the rear fog. Sometimes the fogs and spots are wired so that the rear fog wont work unless the front spots/fogs are on. This although is quite legal is not in my mind the best way to wire them.
Rewiring them is quite simple and a search on this forum should tell you how its done.
Try this link
http://www.exploroz.com/Vehicle/Acce...vingLights.asp

[MattF]

Rip the wiring out for the rear fog light. If it is anything like mine was,
it was an accident waiting to happen. Unfused feed from the battery,
and a twist join partially cover by insulation tape under the drivers side
pillar trim.

You are far better off doing it again so that you know it is correct. May
be worthwhile doing it with the fronts as well. At least you know exactly
how everything is wired in the future if you have any problems, and you
also know it is done safely.

[drdan]

Well, managed to sort out the problem with the rear fog. At least I can get her through the MOT now. Their was no earth connection between the bulb and the chassis, just a 12 V supply from the switchc below the dash. Obviously the current had nowhere to go - I should have spotted it sooner! Why it was missing I have no idea, perhaps the previous owner removed it for some reason! Otherwise it's wired in pretty well. As mentioned the 12V runs from the bulb, back through to the switch below the dash which is powered with a 12V supply from the light assembly somehow (it works correctly with headlights) and has an earth to the ground on the back of the ignition. Just needs an inch of wire to connect to ground at the bulb housing and it will work fine.

As for the front lights, it is now clear as was suggested above that it is those that are controlled by the centre switch and that are blowing the FOG fuse. I think I'll take the advice above and wire them in again from scratch to ensure that they are done correctly when I have a few hours free.

Thanks again for your help.

Cheers,

Dan

[Wild Thing]

Just make sure when you rewire the front spots that you put a relay in the circuit