Blown 100 amp fuse

[ekim]

Driving home tonight, pull out a junction and gave it a bit of a squirt, pulled no problem untill everything when dead, no lights or nothing, turns out it has blown the 100amp fuse on the main lead off the battery, the lead is also quite hot.
Any wild guesses as to what could cause this, is it a common fault or have i got weeks of head scratching ahead of me

[TVR Thomo]

From what i've read on here it's quite common, at the end of the day it's still a fuse! Easy and cheap to replace too

[ekim]

Ok i will try and get one tomoz and keep my fingers crossed, Just a bit odd that the cable was getting so hot

[shpub]

The idea of the fuse is to make sure that it blows before the cabling gets so hot that it melts and sets the car on fire. While the fuses can fail on there on, the fact that the wire is hot is very suspicious. It does look like the car has some kind of short circuit somewhere which is causing an overload hence the hot wire and blown fuse. My first suspect would be the starter or alternator as they are the biggest current devices. An alternator fault can short out the battery (which is why they have 100 AMP fuses and not just as a another thing to infuriate you).

[puffsorted2]

Also very handy item for when some monkey (me ) connects the battery terminals up the wrong way

[theaxe]

ekim said:

Ok i will try and get one tomoz and keep my fingers crossed, Just a bit odd that the cable was getting so hot

This guide may be of use.

[ekim]

Thanks for that guide, Gonna change mine once a year like it says o ply safe. Bit easier job on my 2000 4.0 as its in the footwell just above the battery, not sure if there is one under the car as well.

[That Daddy]

ekim said:

Thanks for that guide, Gonna change mine once a year like it says o ply safe. Bit easier job on my 2000 4.0 as its in the footwell just above the battery, not sure if there is one under the car as well.

Funny you should say that i have two one on top of the batt & one on the offside lower engine bracket(the regular place).

[JonathanT]

ekim said:

Gonna change mine once a year like it says o ply safe.

I get mine changed at the annual service and the old one is usually in a poor state - just a little persuasion makes it crack in half.

[GingaNinga]

Mine went some three years ago and since then I've carried a spare. No need to replace every year though surely?

[JonathanT]

GingaNinga said:

No need to replace every year though surely?

The last two that came off in two successive years were intact but in a very poor state. You could easily see a crack forming in the middle.

The first and original one lasted three years before terminally failing on a French autoroute. The second lasted about two years before terminally failing - thankfully on the drive at home.

For want of a 10p fuse and less than 5 mins of effort........

[MPETT]

I am no electics expert but could it be that the fuse material is quite brittle and its mounting point results in it flexing with the chassis? If this were the case and a crack were to propagate then the risistance of the fuse would go up and therefore generate heat, finaly resulting in it melting/blowing and the wires either side getting hot?

Or it could be corrosion on the earthing points. Re: eathing points, (my bible is on order!,) how many earthing points are there on a Chimera?

Discuss!!

Martin

[chr1sb]

I have a '95 400 & don't have this fuse - at least, not in the location given in 'The Bible'. Is it located somewhere else on some models, or not fitted at all in some

Chris

[JonathanT]

MPETT said:

I am no electics expert but could it be that the fuse material is quite brittle and its mounting point results in it flexing with the chassis?

Don't know the cause, but it looks like metal fatigue to me.

[MPETT]

exactley! repeated flexing resulting in fatigue and ultimatley a crack!

[ekim]

well fitted a new one and done a fair amout of miles since and all has been fine so take it that the fuse had just aged

[AAAndy]

These blow every now and again on Cerberas but very rarely on Chimaeras. At the end of the day it is a 50p part so cheap to change. But would check out if there is a reason as to why it went.