Disco 1 What did I fry?

No idea when it happened but I fried a wire somehow???



It's the W signal wire that goes to the tacho, but if you look at it the cable loops back to a spade terminal that goes to a little black something or other that mounts to the alternator casing.

Alternator charges at full capacity (14.6V) and battery light extinguishes immediately.

Only thing I can think is that I must have forgotten to disconnect the battery one time when I was on one of my welding sprees???

Well, I suspect the rectifier has let some smoke out - the W terminal is half wave output used to drive the electronics in the tacho - so it sounds like the tacho has had a bit more than half wave to do that ....

Disco1BFG said:

Well, I suspect the rectifier has let some smoke out - the W terminal is half wave output used to drive the electronics in the tacho - so it sounds like the tacho has had a bit more than half wave to do that ....

Click to expand...

Wire looks like this

Not the first time I have had a bit of electrical trouble on this thing (see build thread for further details)

You could test the output from the W terminal with a multimeter set to AC Volts - start high and work down

Disco1BFG said:

You could test the output from the W terminal with a multimeter set to AC Volts - start high and work down

Click to expand...

The alternator still charges thought, puts out healthy voltage too, have I hurt it long term?

This bit?



I have got a spare binnacle in my stores just in case I killed the electronics off in the dash lol

Yep, almost certainly that bit - I would test it - but I guess it's a cheap parts cannon to fire - might be worth a look inside first - if it has let go - it'll probably be somewhat crispy

looks like the cable insulation at some time came into contact with the exhaust manifold melting it till it shorted out looks like it happened in the past going by the heat shrink further down the cable
the battery cable looks like it requires moving further away from the manifold judging by the way the insulation is discoloured and rippling

I'd have thought if the rectifier was fritzed it wouldn't be charging... I think Mystery is on the right track, insulation melted or cracked and the the wire shorted out to ground somewhere.

mystery said:

looks like the cable insulation at some time came into contact with the exhaust manifold melting it till it shorted out looks like it happened in the past going by the heat shrink further down the cable
the battery cable looks like it requires moving further away from the manifold judging by the way the insulation is discoloured and rippling

Click to expand...

Tacho was working before the year long weldathon took place, the other side of that W wire is another wire that comes off it and goes to a little black box that is earthed through the casing.

It hasn't run much more than 20 minutes here an there in the last year.

That wire runs quite a way away from the manifold, virtually no chance of it having touched.

would not be quite away when driving and a considerable air flow through the engine bay pushes it towards a very hot exhaust manifold (good job it's not a V8 ) next time you go for a long run lift the bonnet and see if they are