Fog light not working

[Molly24854840]

Hi all looking for some advice, my rear fog light on my 82 T25 is not working, no fuses are b,own, I can make head nor tail of the Haynes wiring diagram, does it need a relay if so what number is it, the garage when they did my MOT said it was the switch I have bought a new one and fitted it but no joy, there is a black box on the right hand side of the engine bay everything is connected in there, I dont know what else to do, thanks

PS I tried a circuit tester in the light cluster no power going to the fog light bulb holder

[ewenmaclean]

Hello,

with these electrical problems you have to be quite methodical - it's good you've got a circuit tester or a multimeter. First of all verify you have power going to the fog light switch, and also that you have power coming from the light circuit. The switch has several wires going to it, I don't have my haynes and I can't quite remember but I think grey/yellow is from the lights (by memory). Check that with the ignition on and lights on, this is live... I'll check my haynes and be back with more wiring colour info for the other ones to check - if there's no other help! I've got a later van but usually the colours of wires remain pretty constant.

Good luck -

Ewen

[bigherb]

There is no relay fitted.
The fuse is not in with the main fuses it is in a separate twin fuse holder next to the relays.
As above the power feed to the switch is grey/yellow only powered when ignition and headlights are on.

[ewenmaclean]

just had a look on mine. As bigherb says - no relay unless you've got front fogs, in which case the grey/yellow is fed from connector B20 (or possibly B18) from the relay number 7 (powered by the X bus) which will switch on with sidelights.

With no relay the lights feed comes from a spade connector on the right of the fuse box, then a grey/white wire goes back there and powers the rear fog light. The earth wire is just an earth for the indicator light in the switch.

You don't have the same fusebox as me I'm afraid as I have a later van, but the principle's the same - I took some shoddy pictures when I rewrired mine for a relay and put in front fogs here:

https://club8090.co.uk/forum/viewtopic.php?f=39&t=78992" onclick="window.open(this.href);return false;

I think in the early vans the fuse for the rear fog light is fuse two - it's on the later ones that it's above the main line of fuses.

So check you've got power from the grey/yellow, and then trace the grey/white wire back and see where that loses power if you do.

Ewen

[pirate-pete]

If you look under the dash you should see a few nylon connectors joining looms together. One of the bigger ones is a four way one - think it is similar to the type you used to see on computer hard drives. The wires from that connector are the ones that go to the back lights so if you apply 12v to the grey/yellow one hopefully your fog light will come on. If not you have a break between the dash and the light unit. I think there is another connector at that black junction box you found in the engine bay so you could try checking if the 12V from the dash is available at the grey/yellow there. If the fog lights come on fine when you apply 12V at the dash connector just follow the wires from there to the switch to see where the fault lies. Good luck.