Thread: Alternator doesn't charge, no tach after shorting it - but it's not the obvious fuses

Assuming that all the wires are still connected and working, you alternator is probably stuffed. It shouldn't be too hard to find a second hand one to replace it.

Could be diodes, rectifier, both or more. BU's idea is probably easiest and go find a second hand unit.

I bet you never do that again...

BIt of a lesson learned there...

If the consensus is that it is the alternator, then I might as well pull it and have a look. Its not an old unit and you can get spares cheap enough. Not a DD so it can sit for a week or two...

Thanks for the responses

With the engine not running, check to see if the alternator B+ terminal has power because if there's a fuse at the battery where the alternator lead attaches, it may have blown. Shorting the terminal with the engine not running can't damage alternator diodes directly. Note that running starter motors drawing 400A doesn't damage alternators and you wont have caused a 400A current draw with some arcing from your spanner.

As Graeme says.

The wire from the B+ to battery is OK. The main 100A fuse is also perfect, as is all others (including fuse #14).
The alternator looks OK internally (ie. nothing obvious) and the regulator/rectifier doesn't look fried (not that it means much with solid state electronics). I replaced the reg/rec only a few weeks ago, so it's as new (notwithstanding I may have internally cooked it).

I'll reiterate that the charge warning (battery icon) light does not illuminate at all now, and hasn't since I shorted it. I know that'll stop the alternator charging, but will it also stop the tacho from reading and/or any other effects? If so then maybe I just need a bulb (yay - minimal $$$$). If not, then it's rebuild or replace the alternator (boo-hiss - much more $$$$$).

I'm temporarily caught without RAVE hence asking silly questions that could be easily looked up otherwise. Lesson learned #2 is keep a copy on a thumb-drive for portability.

Thoughts?

I just grounded out the WL (brown/yellow) wire and the warning light on the dash lights up. So it's definitely not the globe. And that means the alternator is the issue... I should have known BeeUtey was going to nail it first time...

I'm tempted to get a replacement voltage reg for around $45 and drop that in first. No tacho and no charging - both driven off that module (and that module directly shorted). Gotta be worth a shot.... right? And the alternator was a new genuine unit that has only done 15-20k and is in excellent condition.... apart from not working.

Worth a shot if it's not that old. Diodes could also be toast.