Accessing wiring fault

[rosie]

A long while ago I blew a circuit - it powered the interior light, the central locking, the cigarette lighter, the stereo, possibly the clock.

I checked obvious stuff like fuses relays etc. I've had a couple of people look at it since and no one has found out where the fault lies. One electrician said he'd traced it to behind the dash somewhere but I couldn't afford to pay him to go any further with it at that time.

I'm very much an amateur and need to enlist some help from a mate to hopefully DIY mend it, but failing that I thought that if I had to get an auto electrician I could save some money by taking out the dash for access.

Please does anyone have any advice on this? I'm not sure whether it's just a case of finding a burnt out wire and replacing it, or whether it's likely to be more involved. Is there anything to be gained by removing the dash etc?

The circuit blew when I was running the stereo at the same time as a fan plugged into the cigarette lighter (interior blower needs replacing too!)

Been trying to get it fixed for 10 years now, so I think I need some help!
Thanks guys.

[unknownmale]

The most likely cause is that there is nothing wrong with the wiring, you were just drawing too many amps for that circuit, so the fuse popped.

A fuse is just there to ensure you don't overload the circuit with more amps than it's designed to handle. Replace the fuse and don't plug anything more taxing than a cigarette lighter into the lighter socket (Unless you want to run a new circuit for it with higher gauge wire and it's own higher amperage fuse).

If you don't have a blown fuse anywhere and you don't have power to any of those items, it's unlikely to be a short to ground. This would pop fuses. It's more likely that you lack power to the circuit to begin with.

If you're 100% sure it's not a fuse, then it's time to trace wires. You can look in the back of the haynes manual for wiring diagrams, you'll need a multimeter. go through each component checking for power where there should be power...Just pick one of the no operating circuits, you'll likely find the common fault of all of them. The simplest is the cigarette lighter as it just needs a constant power (12v) and a ground. As mentioned, very unlikely that you have a short to ground with no poped fuses, so check the power feed. Thats one wire from the back of the lighter (probably red, can't remember). This should have 12v all the time (Regardless of the key being in the on position)...Keep tracking that wire all the way to the fuse box...Probably broken, or someones put an inline fuse somewhere along the way which has blown.

[Nugg1985]

I would look at taking out the centre console not the whole dash as you can get to most of the wiring for the systems you are having problems with then, hopefuly if there is a problem with wiring you should find it quite easily

[rosie]

Thanks guys. It's definitely not a fuse cos I replaced it as soon as it blew (unless someone has connected an inline fuse as you mention David). The auto electrician said he traced the fault to behind the dashboard. I'll start with the cigarette lighter and see how it goes. Thanks for the advice.

[unknownmale]

Yeah, not a bad shout just pulling the radio out, 30 years of DIY stereo wiring may well be cause too!

[mr.brown]

It's possible that you've melted one of the circuits inside the fusebox. I would check, with a voltmeter, whether power is actually getting to the fuse.

[rosie]

Thanks. It's had a couple of new fuseboxes in the years since the circuit blew so I'm confident it's not a problem within the fusebox itself (water leaks into the fusebox have been an ongoing issue, so I took out the glove box to make room for an 'umbrella' over the fusebox a few years ago. It's been ok since)
I'll have another look at the stereo wiring. I took the stereo out years ago - probably the last time I tried to fix this - and it never went back in again. I could do with a working stereo to mask the sound of the rattles and bits of car slowly falling off

[rosie]

Finally got chance to tackle this over the weekend. Turns out that the cigarette lighter (which was the obvious culprit, given that it was in use when the circuit blew) was shorting out.
We couldn't work out how to remove it so it's just disconnected for now. Does anyone have any tips on how to get it out please? I couldn't feel any obvious clips or anything.

Anyway, with the lighter disconnected I now have working central locking, clock and stereo. Music in the car today for the first time in a decade was pretty sweet!

Thanks for all the advice.