Help - Alternator trouble

paulp666 · May 18, 2014

Hi Folks,
Hope you are all enjoying the sunshine

Ok, about a week or so ago I changed the oil sump on my '96 110 CSW, a while later while driving it the alternator/charge warning light came on

After measuring the charge I was getting 11.8v steady.

I needed to change the aux belt and tensioner so today I have done these and fitted a new alternator. It was an identical denso unit. All I had to swop over was the small black box connecting from the W terminal to the body of the alternator.

On starting, I am still not getting any charge

((

Your suggestions would be most welcome as I am totally stumped!

Cheers
Paul

Naylz · May 18, 2014

Your problem is that the alternator is not "exciting", the thin wire that goes to your alternator may be the fault. To test this theory run a live wire direct from your battery, start the engine and then touch the live wire on to the terminal the thin wire was/is connected to. You should hear a slight change in engine tone and your alternator should now be excited and creating 14v charging.

Naylz · May 18, 2014

Oh and then just trace your thin wire back to hopefully find a break/ short where it has rubbed against something. If it's a 300tdi my guess would be on the air filter bracket

.

Naylz · May 18, 2014

Er can I ask why you fitted the old black box to a new alternator? It could well be that too, the black box is the voltage regulator and when broken give the same issue you have. Sorry missed that

paulp666 · May 18, 2014

Hi,

Thanks for the info

The new alternator didn't come with a "voltage regulator", so just presumed I needed to swap it over! Is it likely that the new one is built in?

There are two thin wires connected to the alternator, which is h exciter wire?

Thanks
Paul

jamesmartin · May 18, 2014

presumably the little black box is the suppressor for radio , b+ has battery thick lead and d+ is exciter wire from dash charge light w is take off for rev counter, d+ must have 12v with ignition switched on

paulp666 · May 18, 2014

Okey doky, just been out and found the exciter wire and then tested it and it was at 0v. Started tracing the wiring back and around the oil breather pipe, found a little fire in the making!!!

Opened up the loom and luckily only the exciter wire rubbed through. Have repaired the wire and all is good now

Well at least everything is new now and I have a spare alternator. Is there any way to test an alternator off the vehicle?

Thank you for you help

Paul

Naylz · May 18, 2014

Glad you sorted it, it's exactly what happened to mine, I too now have a spare alternator and a repaired exciter wire

Help - Alternator trouble

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