Diagnose my alternator.....por favor

My charge light has just come on recently and my voltmeter is only showing 12v with the engine running. I changed the belt and it was ok but now the lights back on and its showing the same voltage again. Checked the output from the alternator and its only showing 12.4v with the engine on. Am I right in thinking its on its way out? Or are there any repairable/replaceable parts on it? It's a disco 200tdi

Cheers in advance.

check your main earths, had similar symptoms on mine not long ago (few weeks) not long after started getting the christmas tree effect, sorting the earths gives me a nice voltage

Cheers dude, will have a look later if the rain stays off long enough

If all the connections are tight there are two possibilities for the charge light to be illuminated, first is the alterantor is faulty, the second is if you are trying to draw more amps (ie lights etc) than the alternator can supply. The second is unlikely. You can purchase a brush a regulator pack to repain the alternator. Here is a link Regulator & Brush Box Assembly - Alternator - Aftermarket at www.rimmerbros.co.uk
Its very easy to do. Just remove the alternator and replace this unit on the rear of the alternator.
Cheers

It's amazing how quickly a battery will discharge through poor earth connections!

I would think that you should be looking at about 13 to 14 v regulated.
That means that when started you should be able to rev the engine and the voltage should stay the same at fast idle as well as idle. It may flick a bit but not much.
As above though - check you earth straps to engine/gearbox first

14.2-14.7Volts

or take the motor to Halfrauds who will test it free.

Either bad earth, or knackered alt, id say the 2nd

Well I've disconnected and cleaned all the earths but still no luck. What's strange is that if I go over a bump or pothole the charge light will flicker or go off then back on in an instant and the voltage will shoot up as if it is a loose cable or something. But all cables are perfectly fine

the_wolf said:

Well I've disconnected and cleaned all the earths but still no luck. What's strange is that if I go over a bump or pothole the charge light will flicker or go off then back on in an instant and the voltage will shoot up as if it is a loose cable or something. But all cables are perfectly fine

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Could be loose within the alt the wire to the light could be the problem as it won't charge unless the light is out

Check connections again or it could be a dodgy wire with a break in it.

G

Is it simple enough to take off an open up for a look? Never mucked about with alternators before which is why I'm a bit clueless

Looking at the photo below, which wires could potentially be a problem inside? Unfortunately it doesn't list what each one does and just calls it 'wiring harness'. All other cables going from alternator to starter motor and all earths are secure and clean.

Happened again this morning when I drove over a bump, the light went off for about two secs and the voltmeter jumped up to show what it should so it definitely sounds like a loose cable/wire

D+ wire on the alt

200tdi ayre said:

D+ wire on the alt

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Cheers dude, will have a look at it after work today

Well its definitely the D+ connection as when I took the plastic bit off and wiggled it the light went off but now its back on again. No worries, at least I know what it is. Problem is that the plastic bit has now gone missing I don't understand where as I had it in my hand, sat it on the wing and its just totally vanished.

Many thanks for the help. Guess I will be off to the scrappy after all even if it is just for the plastic thingymabob

Nope its the small triangular type bit that goes over the top of the D+ connector. No idea what its actually for but I'm sure if it doesn't turn up ill be able to find one somewhere. Pic I put up probably wasn't a good representation as its a 300tdi alt but I assumed the wiring wouldn't be a whole lot different