Any idea why fuse keeps blowing?

[davidtrainor]

Hi i recently bought a 1998 saab 9-5 2.3 turbo and all was well until i plugged in my sat nav and it promptly died from receiving no juice from the cigarette lighter. I tried both the rear and front cigarette lighters but to no avail. I have replaced the fuse (no 34, 30 amp) 3 times successively and each one blows in turn when the ignition is turned on (quite spectacular to watch on a boring day). I looked on the net and it mentions a short of some sort but i am going in blind here and any advice would be great!

[_rubinho_]

davidtrainor said:

I have replaced the fuse (no 34, 30 amp) 3 times successively and each one blows in turn when the ignition is turned on (quite spectacular to watch on a boring day)

fk it, just use a bent nail next time. That won't blow!

ETA: While you're at it, why not tape down the levers on all of the circuit breakers in your house too!

Edited by _rubinho_ on Thursday 8th April 14:06

[Buzz word]

If the fuse is blowing on ignition on with no sat nav plugged in the fault is with the car. If you can turn the ignition on and the fuse is ok and only blows with the sat nav in that is probably causing the fault.

The fact it blows easily an repeatably proves there is a fault. Check it out before you have a bigger problem. Try removing the lighting elements and see if it stops, then try looking for conductive debris in the sockets, just work back down the circuit until you find the problem. Dont just keep replacing fuses, it's a waste of money. Definatley do not put a bigger fuse in.

[Silverbullet767]

It's drawing a massive current, that's why it's blowing, I'd hazard a guess that the cables are bare and touching to ground somwwhere.

Try a resistance test using a multimeter when the car is off.

[The Wookie]

I'd add a supplementary guess that the end of a charger or some such has dropped off and wedged itself inside the socket somewhere.

ETA Failing that, it'll almost certainly be the socket itself or the wiring on the back of it, unless the car is seriously badly wired there shouldn't be any risk of bare wires shorting against the chassis, and I'd hazard a guess that there would be other issues with the car if that were happening

Edited by The Wookie on Thursday 8th April 14:30

[davidtrainor]

yeah currently in the process of trying to pull the housing out to get a better look at the wiring etc. not keen on the bent nails or bigger fuses idea lol. anyone pulled a 9-5 apart before the centre console is a nightmare.

[RV8]

Is that fuse for just the lighter or is it for other devises as well. When the horn on my car wasn't working I figured the horn was at fault, it turned out to be something unrelated using the same fuse which had shorted in bad weather. Just check the other stuff that is used off that fuse and see if it's faulty or has a bad earth, or if any crap (eg foil wrapper) hasnt just fallen inside the lighter sockets.

You didn't screw anything (mount etc) through the dash and possibly go through a wire did you.

[davidtrainor]

hello RV8 valid points all of them but no it's a solitary fuse for the cigarette lighter x2 and no screws or mounts going through the dashboard. tried it with the 'amp tester' i think to see if there is current and there is in both sockets. i have pulled them apart and spotted nothing new and to be honest i am waiting for my old man (65 lol but a game old lad!) get back and put some of his engineering know how into the situation.

could just wire the sat nav to a spare car battery i suppose (no spares i suspect). got a 730 mile run to germany on sun and quite fancy having the sat nav lol.