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        General >> Problems >> Fuse keeps blowing
        
(Message started by: baglady on Aug 13^th, 2007, 10:26am)

Title: Fuse keeps blowing
Post by baglady on Aug 13^th, 2007, 10:26am

Hi everyone, newbie here - please be gentle...

Here's my problem:

I was stuck in that horrendous M25 debacle on Friday so crawling for about 4.5 hours, aircon blasting. When I was nearly home, all the instruments lights went, the aircon went and I could not open the windows or the sunroof. The car was driving well (steering, brakes, indicators & lights all working) so I continued home and made the stupid error of stopping at a shop 10 mins from home for milk. When I got back in the car it refused to start...

After investigation (used the fault finder on this site), discovered fuse 16 (electronics) had blown. When I replaced the fuse, all the instrument lights came back but as soon as I tried to start the car, the fuse blew again. I guess this is a short somewhere but I've no idea really where to start looking.

Any clues gratefully appreciated. I've had a search in this forum but haven't found anything so far so if there's a thread that might help me, please post the link.

Oh, and please, no jokes about women drivers, I think I've heard them all now :(

edit: I probably ought to mention it's a 1997 Ultima, Auto

Title: Re: Fuse keeps blowing
Post by Simmo on Aug 13^th, 2007, 11:25am

That fuse is 7.5 amp. The ones controlling the Windows 25 and 26 are 30amp as is 28 which is for the sunroof. Try pulling those out and replacing 16. While you are at, in the other box, fuses35and 39 which control the air compressor and the fans, also 30 amps, could also be pulled. It's a shot in the dark but reading your post they seem to be the most likely suspects in view of your experience. IF the car starts with these removed then replacing each one in turn should identify the faulty circuit. Before you go removing all these make sure that the likely units ie: aircon etc are switched off as this may enable the car to start depending on the type of fault. Make sure you have more than one 7.5amp fuse!!. Good luck and let us know how you get on.

Title: Re: Fuse keeps blowing
Post by baglady on Aug 13^th, 2007, 11:30am

Thanks for the suggestions - have got 6 spare 7.5 amp fuses so off to have a go now. Will report back :)

Title: Re: Fuse keeps blowing
Post by baglady on Aug 13^th, 2007, 12:27pm

Well, we pulled fuses 25, 26, and 39 (there was no fuse in 35). Replaced the F16 and this time it was different. No instrument lights came on but the fuse blew as soon as we turned the ignition switch to position 2 even before attempting to start the car. Replaced the pulled fuses (none were blown) but same - as soon as the ignition is turned to pos 2, the F16 blows. I'm down to 2 spare 7.5amp fuses now :), good job Halfords is close!

Came home for a cuppa and a re-read to discover we'd forgotten about F28. Will go back after drinking tea and try that one just in case.

If only we could get the car started, I could drive it home (which is about 1/2 a mile) and the investigations would be somewhat easier. I'm not looking forward to towing it much - our other car is a Ka with a missing towing eye!

If anyone has any more ideas before we go back in 10 mins or so, please post.

Title: Re: Fuse keeps blowing
Post by baglady on Aug 13^th, 2007, 1:33pm

Well, we pulled every fuse that wasn't needed to get the car half a mile down the road but no joy - exactly the same - as soon as the ignition is switched to pos2, that F16 blows and the car won't start.

Sigh :(

Title: Re: Fuse keeps blowing
Post by Alastair on Aug 13^th, 2007, 1:56pm

Hi Baglady

Is there water lying around in the fuse boxes. Well known culprit with sudden electrical problems

Good luck

Alastair

Title: Re: Fuse keeps blowing
Post by baglady on Aug 13^th, 2007, 1:59pm

No, no sign of any water or dampness in either fusebox.

Title: Re: Fuse keeps blowing
Post by TiberiuS on Aug 13^th, 2007, 2:15pm

Hi. I'm just looking through the diagrams, problem is that fuse feeds various circuits. My guess is that a hard short would be in the loom or one of the connectors somewhere, or in the fusebox as Alastair says. Fusebox and its multiplugs are the favourite for a short circuit.

Hope this helps :).

EDIT: Fuse 16 feeds the instrument panel warning lights and provides the overdrive switch input to the powertrain control module (ECU) if this helps at all.

Title: Re: Fuse keeps blowing
Post by baglady on Aug 13^th, 2007, 4:15pm

Gave up and am getting the car towed to a garage tomorrow morning. It's sadly not something I can fix so I'll just have to bite the bullet and pay. Sniff.

Thanks for all the ideas though, hopefully it won't be too expensive.

Title: Re: Fuse keeps blowing
Post by TiberiuS on Aug 13^th, 2007, 5:23pm

Probably just a simple short on the loom or fusebox somewhere, if the garage knows what they're doing it should be a simple job.

Maybe an auto-electrician would be better? :-/

Good luck, keep us posted :)

Title: Re: Fuse keeps blowing
Post by baglady on Sep 3^rd, 2007, 8:28am

Well it did take a while but the car is finally fixed :)

Once the dashboard was off and the wires traced, they found a wire trapped by a screw that had rubbed and rubbed and finally worn through and shorted. We could see in the service history that there had been another electrical problem a couple of years back and we can only guess that whoever fixed it then trapped the wire when they put the dash back.
Once the wire was freed fron the screw and reinsulated, the car burst back into life and all was once again well.

So cost of fixing it was a couple of hours of investigation work but no parts needed.