New alternator????

Driving to work the battery light came on, ammeter indicated discharge, and tach was not working. Pulled over and the belt was still on and the electrical connections were tight. Do you think the alternator quit just like that? The truck has shown no precurser to a degraded charging system.
My question is does this sound like a bad alternater or is there something else I can check? My truck is in the parking lot at work, and if it does start, I hope to drive it home and work on it in the garage.
any ideas
Thanks
Jim

Sturgeon,

That's exactly what happened to my 99 about 5 years ago. Noticed the Tach read 000 rpm at 35mph. Mine happened on a 3 day weekend, Labor Day. 2 days w/o A/C in the Calif Valley.

I ran all the tests I could think of, including beating it with a 2X4, hoping it was a brush that was stuck. Nothing worked.

We drove our truck for the next three days, though minimally. Used jumper cables to charge the batteries up, from the other diesel PkUp we have.

Alt had died. Warranty job. Doesn't look that hard for the next time. Instruction for installation says remove the NEG connection from the batteries.

HammerWerf

Yep,

Some the tach starts getting flaky or quits and it keeps charging.

The ones that quit charging the tach goes with it. Normally a sudden failure.

Probably an easy fix if it's worth it to you to take it off and get it to a shop.

Jim-
Also give a check to the alternator's output lead (wire) . On mine there's a fusible link in this lead. If any question, consider renewing the lead as well.

I'm off tomorow and going to work on it. I'll check the link. There was a shop in town that used to rebuild alternators and did a good job, I'll check to see if they are still around. Autozone has the alternator for $140 and in stock, so I've got options and the truck is in the garage so I'll be dry working on it!

Took the alternator to an auto electrical shop and they repaired the alternator for $60. Turns out the rectifier went bad. Re installed and all is well. $60 is better than the $140 I was quoted for one from AutoZone.
Thanks for relpys
Jim

And it's still all original too!!!!!!!!!!

Yes, there have been times when I've bought parts that were listed to fit but were not quite right
Jim