The Big Fuse

[airwalk]

I am having major electrical problems with my Cerbera. The rev counter doesn't work and the battery goes flat after 15 mins of driving. I have been told that it's probably the 100A fuse under the bonnet. I've checked this and it seems intact although it's a funny looking fuse (just a strip of metal). For what it's worth I'll just replace it anyway. Does anyone know where I can buy one easily?

[gazzab]

buy one and a spare from dealer !
It coud have a hairline crack you cant see?
Sure it isnt alternator playing up?

[airwalk]

I don't think it's the alt. I tested the fuse in two different ways with my multimeter. Firstly, I disconnected the battery and checked the fuse for continuity between the two terminals. Secondly, I left the battery connected and checked for 12V positive at either side of the fuse with my other lead connected to the chassis. I didn't get a continuity reading on the fuse and got 12v at one side of the fuse and only about 3v at the other. My experience of electronics tells me that this means the fuse is goosed. What do you think?

[TVR SLag's BiL]

If the fuse has not been changed for a while it will have a high resistance. Its only pence to get one from a dealer or good electrical shop, well worth the time and money.

[Byff]

airwalk said:

My experience of electronics tells me that this means the fuse is goosed. What do you think?

Yes, I think it's goosed.

[mike_e]

If you have a meter then measure the voltage either side of the fuse with the engine running, should be around 14V on both sides. If you get 14V one side and 12V on the battery side then its the fuse. If 12V or less on both sides then it's the alternator or wiring.

From what you've already said it looks like the fuse. Mine has had problems twice, once it snapped the other time it just came loose. Always carry a spare, it's a very common problem. The Battery light dosen't always work but the Rev counter is a good indication!

[and]

does the rev counter die suddenly or does it go through a phase of jumping around when you change rpm ?

[mike_e]

and said:

does the rev counter die suddenly or does it go through a phase of jumping around when you change rpm ?

Found mine tended to leap about over 3000-4000 rpm but generally only when accelerating, more load from the fuel injectors I suppose.

[beej]

Definitely replace the fuse.. don't put it off for the sake of a few pence worth of component (even though its a bit awkward to get at). The hairline crack syndrome is quite common, impossible to spot and the first you know is the electrical components start to die one by one as the battery gives out. Mine went in Belgium.. and there my car stayed for 3 weeks whilst the RAC farted around trying to repatriate it. I was a prize prat for failing to take a spare.

Of course, if TVR had designed the component and location so that it didn't keep breaking...

[and]

Where is it on a speed six and what's the best way to get at it ?

[airwalk]

My rev counter stopped working totally. Harrogate Horseless Carraiges have been kind enough to put me a fuse in he post. Having taking the old fuse out, it had actually broken where it bolts in to the fuse holder. Great TVR's, aren't they?

[TVR SLag's BiL]

Great all sorted!