940 blowing fuse 1 and not starting

[mocambique-amazone]

see post 16

behind the ABS at the inner wing side will be the RSR, this is powered by fuse 1

(can't remember rhd cars, shoud be the same place)

[Laird Scooby]

Originally Posted by coolpurks

Ok so I have found a bulb holder for one of the rear lights with a bulb in it will this work for the tester? I’ll solder a couple of wires on.

Just thinking back, the only wiring that could have possibly been disturbed, was any wiring near to and including the open bonnet sensor, and the wiring to the fan relay, and any other wiring that appears to go towards the back of the headlights near the fan/radiator. I moved this out the way to remove the intercooler. I clipped it all back in place after I re-fitted the intercooler – do you have any idea whether any of these wires could be linked to fuse one? No worries if not!

Originally Posted by mocambique-amazone

see post 16

behind the ABS at the inner wing side will be the RSR, this is powered by fuse 1

(can't remember rhd cars, shoud be the same place)

Kay beat me to it! If necessary, emove the intercooler again and just make sure you haven't trapped any wired - it's easily done, too easily in fact!

[coolpurks]

Cheers, I have now freed up the wires as much as possible but run out of fuses! I will make up the tester, is the idea to them put that into the fuse box? Fuse Position one? Or is that horrific idea! I will have a play around tomorrow hopefully I’ll let you know how I get on. Thanks for all your help it’s really appreciated

[coolpurks]

If I have caught it though is that not likely I’ve damaged it or will sometimes just freeing it fix it? Cheers!

[Laird Scooby]

Originally Posted by coolpurks

Cheers, I have now freed up the wires as much as possible but run out of fuses! I will make up the tester, is the idea to them put that into the fuse box? Fuse Position one? Or is that horrific idea! I will have a play around tomorrow hopefully I’ll let you know how I get on. Thanks for all your help it’s really appreciated

Originally Posted by coolpurks

If I have caught it though is that not likely I’ve damaged it or will sometimes just freeing it fix it? Cheers!

Now you know why Ash and i both said make the short-tester first!

The 21W bulb won't really be good enough although it might do at a pinch. Once you've made it, fit the wires in place of fuse #1 and then start checking to see if you've still got the fault. You can also see how quickly the fault develops, whether it's the instant you turn the key to KP2 or whether there's a delay of a couple of seconds etc.

You may have freed the cables but they may still be strapped somewhere and/or damaged so they're still shorting out. Only way of doing it is to inspect the whole length of them in the area they would have been trapped.

[coolpurks]

Thanks I think I have this- so when the bulb lights there is a problem and if the bulb no longer lights all is good? I am assuming I won’t damage anything by doing this, I only ask because the fuse would normally blow out cutting the circuit but I assume this is drawing the voltage protecting the other components? Thanks!

[aardvarkash10]

the tail light bulb is not big enough - it has to be a headlight bulb. Wired in parallel (both filaments running) a headlight allows about 8A of current which is plenty to run most circuits, but low enough to not damage most circuits in a short.

Yes, you are right about the technique - if the bulb glows bright, you still have a short.

Yes, you plug the bulb in where the fuse goes - instead of the current flowing through the fuse, it flows through the bulb.

[aardvarkash10]

Originally Posted by Laird Scooby

Now you know why Ash and i both said make the short-tester first!

You may have freed the cables but they may still be strapped somewhere and/or damaged so they're still shorting out. Only way of doing it is to inspect the whole length of them in the area they would have been trapped.

If you have smelt smoke, there is a good chance that the short is now permanent. Either a live wire has melted itself onto an earth point (including an earth wire) or a component has failed internally and connected a live to an earth. This sometimes happens in relays that fail mechanically.

WIth the dim bulb tester, the easiest way to isolate the location of the fault is to disconnect the harness at each major connector, one at a time.

[aardvarkash10]

use one of these



with one of these

[coolpurks]

Thank you I will make the tester try and disconnect everything listed in post 16 connect to fuse 1 and then if the bulb doesn’t glow connect 1 at a time...

Is white ground on that bulb holder? Cheers!