At last....... It turned out to be the tail wires that go to the battery.

I guess they'd just had their day and called it a day.

I replaced them as suggested with new and larger wire (35amp) got some decent connections and wired them in along with a 30amp fuse on the tail wire that had obviously been getting hot. (The fuse was just a safety measure incase there was a problem further down the loom. But it appears not.

Now I'm getting 13.5 volts to the ecu at idle with no ancillary electrics on.

And with lights on full beam, and wipers on full chatt, I'm still getting 12.5 volts at the ecu.......And the fuse hasn't blown.

At last.

Assuming this was the problem and I've solved it, I just wanted to say a big thanks to everyone who gave me suggestions as to what the problem might have been.

At least now I know that every earth lead has been checked, cleaned and is working properly, and I've gone through the fuse box connections, relay connections and about every bloody electrical connection on the car. So electrically, it's as good as it'll ever be.

Big thanks to everyone, and I'll keep my fingers crossed that the problems solved.

Basically, I have good power going to the ecu, even with ancillaries on. So no Karl can get off his butt and finish of the mapping.

Best Regards and thanks for your patience with me.

Jim (Know more about car electrics now than I've ever done....Which still isn't much).

 

nice one jim

 

 

HORAYYY

 

glad u got it sorted mate i have been following the threads

 

jim i took amp readings and are with nothing switched on red wire 4 amps red and blue wire 0 amp red wire that seems to be in a seperate loom 0 amp and now with every thing switched on red wire 19 amps and 29 amps when rad fans kick in red and blue wire 31 amps and red wire in loom of its own 26 amps and my fuel pump is on a circuit of its own that pulls 7 amps on tick over so you will have that load on one of the cables i think the red wire that seems to be in a different loom is for heated screens the black tails on my loom got verry hot so looks like i will be changeing them but think 40 amp fuses may be advised
cheers alan

 

well done

 

Nice one mate. I had electrical prob on my escos that was a right pain in the ass. Turned out after 4 months of fooking about to be the 3pin connector at the MAP sensor. Cost me 2 quid to fix


Didnt DAZC say it could be the tails?

 

ALAN : Thanks so much for that Info.

I'll replace the 30amp fuse with a 40amp (Just to play it safe)

Thanks again for taking the time to do that. The fuse is only a safeguard as I didn't know if I had problems further down the loom. But with the three tail wires changed for new 35amp wire it seems to have cured the problem totally. No more power to ecu problems, getting plenty of volts to the ecu now, and no more hot wires.

And Yep, DAZ C had it pinpointed from the begining.

Thanks again Alan

Really appreciated.

Regards Jim

 

Jim remind me before the next meet and I'll bring my clip-on Amp Meters and we can check exactly what each cable is drawing current wise.

 

Cool very pleased for you Jim. Bet you can't wait for it to be fully mapped

 

Just read your other post to Ryan about calling in Thursday night. I live just down the road from Ryan, call in if you want and I'll check it for you then.

 

Jim. It might be an idea to keep a few spare fuses in the car incase it blows. Would be a bit of a bitch to be caught out if it blows...

 

Are these 'tails' the "fuseible links" that you see on the wiring diagrams?
ie, cables that inherently need to carry stout current, but are up front of the fusebox protection?
If so, are they just copper of smaller gauge than the rest of the cable, that will blow first if there's a catastrophic problem, or made of some more exotic material?

 

I think the fusible link wire is a very soft, flexible metal (possibly finely braided copper or something softer like tin?).

Glad to hear you've sorted it all now. You might find your alternators and batts last longer 'cos they don't have to work as hard to keep power flowing nicely

 

 

Hi Guys,

I'll try and answer each question :

Yes, the tail wires are fuseible links and are before the fuse box (3 of them Come from the pos terminal on the battery) and are designed to blow/burn if you have a major electrical problem in the loom. God knows why they didn't run these three cables through a fuse box ...... They come off the battery and are all black wires, about four inches long and then attach to larger cables. As these are designed to fuse first if theres an electrical problem, if you replace them with larger wires, then you should put inline fuses in. I used 35amp wire and 30amp inline fuses, and it seems to have done the trick.

In the short term I'll be carrying a few fuses with me (Just Incase). The 35amp wire that I used to replace the tails is still smaller than the wires they lead too, but larger than the tails I replaced.

This problem caused me days and days of checking every terminal, every earth on the car, and as DAZ C correctly suggested, it was down to these wires (One in particular) all the time. The one that appears to give problems on older cars (purely down to degraded wires) is the one which leads to the thinner of the two red leads. There is one that leads to a thick red wire, this apears to give no problems. One goes to a red wire with a blue line in it, this appears to give no problems. But.... The one that does give problems and appears to have given problem on many peoples cars is the one that leads to the thinner of the two solid red wires. If your cars original, and nobodys messed around with your terminals on the battery then on the adaptor plate on the pos terminal of your battery, the wire that causes the problem is located on the small middle terminal (There are three). I just hope this thread helps out other people in the future.

CHRIS : I'll be in abit of a rush today, so I won't be able to pop around, but I'm at the surrey meeting on sunday. WHERE IS EVERYONE MEETING (Assuming we're going there in convoy) Could you bring your amp meter with you ???

 

Nice one Jim, glad its finally sorted

 

good description Jim!
The bit I'm trying to understand is why these tails are effectively ending up "high resistance" - if they are plain copper, this can realistically only be due to corrosion in the termination or in the actual wire itself due to water ingress (when all the copper cores go black..).
Are we essentially concluding that it's down to these effects and old age?
If so then there they could be renewed with fresh terminations and similar gauge wire to maintain the 'fusible' link function..

 

Tks Paul

It was really doing my head in, and probably everyone else reading the posts.