Alternator Died. Why?

[cc333]

So I was driving uphill today, and the battery warning light came on and the volt gauge went low. Apparently it's the alternator, but I'm not sure what would've caused it to die so suddenly.

Short of the alt itself sortof breaking internally, is there a fuse somewhere that could've blown?

This is the same old '94 K2500....

Thanks,

c

 

[Phat Guy Garage]

check the gauges fuse if it has 1,if it does and it is good,check for power to the big red wire on the alternator,if that is okay,the alternator has failed.Probably a shorted diode has caused the failure

 

[cc333]

OK, I'll do that.

EDIT: I forgot to say that there is a Gauges fuse, and that I didn't think to check it, because I thought that if it were blown, the whole gauge cluster would go dead, but I guess not?

Anyway, I'm not at the truck now, but I'll check it ASAP.

Thanks!

c

 

[Hipster]

Alternators are not designed to work at 100% duty cycle so a weak battery that won't fully charge can smoke an alternator.

 

[cc333]

@Hipster That's good to know, thanks!

The battery is less than 2 years old, though, and has consistently tested good, so I sort of doubt it could've blown the alternator. But who knows?

Of note is the fact that it's always been kind of "whiny" since we bought it in mid 2017. Could could that be an indication of alternator weakness?

c

 

[GoToGuy]

How old? How long has been in service? Brushes wear out, diodes have some issue and die, bearings fail from many causes. Without an autopsy cause of death is unknown. Testing will tell if it's dead. Good luck.

 

[someotherguy]

They do just go bad, like pretty much everything, eventually.

Don't overlook a loose connection from the harness. They do get a little flaky and will quit charging. Give the connector a gentle wiggle while it's running, see if it starts charging again. You'll know it right away as you'll hear the difference when it kicks in..

Richard

 

[cc333]

How old?

I'm not exactly sure. It looks a bit newer than everything else under the hood, so I suspect maybe it's been replaced at least once already, but again, not sure.

Be that as it may, the odometer indicates about 106k miles. I can't substantiate this, as I don't see any obvious signs of tampering, but I wonder if maybe it has been rolled back or something, as the sorts of issues we've been having (blown transmission, flaky electronics, failing ignition coil, distributor, radiator and water pump) seem more consistent with a heavily used 200k+ truck, don't they?

Don't overlook a loose connection from the harness. They do get a little flaky and will quit charging. Give the connector a gentle wiggle while it's running, see if it starts charging again.

You mean that one that comes out the side? That was the first thing I checked, as it popped off once before (but alas it wasn't the problem; it was still solidly in place thanks to the zip tie I used to fix it).

I'll be back by the truck tomorrow, so I'll bring a miultimeter with me and check the gauges fuse. I sincerely hope that's the problem, because I really don't feel like paying more big $$$ to a shop to change out the alternator right now!

It's like a $30k $5k truck!

c

 

[cc333]

OK, just checked it out. Gauges fuse looks good, and I read 12.31V at the alternator, so it looks like it's shot.

Does anyone know the part I should get? I searched, and I got 88-93 and 95+, so does that mean 94 is an odd year?

c

 

[cc333]

I tried searching again, this time explicitly adding '1994', and I found some on eBay.

One is equivalent to stock (105A) and another is high output (300+A). Is there any harm in upgrading to the high output model, or should I stick to stock?

c