Calling all you electrical boffins!

[Judderi]

Unfortunately i have had an electrical fire and my car is pretty knackered. Ive found the wire in question but would like to know what the thing it connects to is. Its the yellow wire that runs under the air box with the headlight loom. The yellow wire makes a diversion at the lights down towards the floor and connect to some sort of ceramic pipe about 10cm long mounted to the chassis. Whats this ceramic thing and whats this wire do?

[tobz.]

Thats the interior heater fan resistor, when you run your interior heater fan on the slower speeds the voltage to the fan needs to be divided down from 12volts. The excess volts are therefore 'burnt' using a huge resistor (the ceramic pipe).

[GTI EDITION (aka LTD)]

Sorry to hear of your trubs  
It sounds like the wiring to the DimDip resistor from what your describing(they were done away with on new cars back in about 98ish)
How badly it the car damaged? Hope it's repairable

[mjamoose]

I'm going to have to agree with Vento on this one, it sounds more like the DimDip Resistor (Disabled on my car), Tobz I would have thought that the heater fan resistor would have been built into the rotary switch unit on the dash.

[Judderi]

tobz this seems to be linked to the lights, are you sure were on the same lines?

Vento whats the dimdip? Do you mean like dipped beam on the lights? Mine is an early mk2 on a G plate, i.e hazard on dash.

I tried replacing the wire last night with no joy so i suspect there is more damage, so im gonna take it to an auto electrician.

[mjamoose]

Prob the best bet!
The Dim dip is basically a resistor, so that when you switch the lights on to the first position inside the car, you get the sidelight bulbs and the headlight bulbs on, but the headlights are dimmed down, if that makes any sense - they are dimmed & dipped beam lights.

[Judderi]

I'm going to have to agree with Vento on this one, it sounds more like the DimDip Resistor (Disabled on my car), Tobz I would have thought that the heater fan resistor would have been built into the rotary switch unit on the dash.

What do you mean disabled on your car? Is it worth me disabling it on mine. This would save me having to run a new wire through the bulk head into the engine bay.

[mjamoose]

I've got one of Dizzies uprated lighting looms in my car, just gives extra power to the headlight direct from the battery.
You don't really need the dim-dip on because it doesn't make a difference really, tbh and it's not a requirement in the MOT.
To disable just pull the wire out of the top of the resistor!

[Judderi]

Ive got one of dizzies looms too. Will disabling it do away with my sidelights? Cant be having this as i have angel eyes to show off! 

[mjamoose]

Nah, basically it brings the main lights on to the same brightness as the side lights, if anything it'll make the angel eyes stand out more!
One thing to point out tho is that if you have had an electrical fire, you MUST check all the surrounding loom wires for any signs of damage!
Disabling the resistor will probably cure the fault, but you've gotta find out what caused it in the first place.