Car Questions
RepairPal is your advocate for car care advice and guidance

Alternator won't charge when the car is started when warm.

(1999 Chevrolet S10)
in Glenside, PA on September 27, 2014
When I start and drive it from a "cold" start, the alternator charges as expected; the voltage gage shows in the 14.5v range. When I shut it off and start it back up while still warm (like at a gas station) the volt meter shows around 12v with the battery light on indicating no charge.

Here's what I did so far:
Replaced the alternator (it was old anyway but the problem remains with the new one)- I will take this new one out (it's a remanu) a try a different one.
Replaced the ECM/PCM but still there (seems to run better, oddly enough)
Checked all the grounds - fine
Checked power directly from the alternator both hot and cold: shows the same results as the volt gage.
Checked power at battery, same as volt gage.
Tried different batteries: same result

Displaying 1 answer & 1 comment
Popular Answer
of Ambler Tire Co., Inc. on September 27, 2014
I seem to remember some GM`s having a ground problem with the alternator bracket to motor connection.Get a jumper wire heavy gauge or jumper cables a supply a ground from the battery negative to the new alternator body.If it helps you have a poor ground issue.
Sign in to reply
on October 04, 2014
Just tried that, no dice. I'll take this alternator back to the store. That's the only thing I can think of, and I doubt that is the problem.
Get a repair estimate
RepairPal estimates are guaranteed at over 2,000 quality certified locations nationwide.
Or interested in getting a repair? Find a Shop

Similar Questions

View answers to similar questions from RepairPal's community of auto experts and enthusiasts.
trouble with car starting it doesn't die while driving it only when you stop it won't start again autozone check the...
I changed the belt prior to the harmonic balancer & 4 times after the balancer-even tried a gator back belt, chan...
Didn't find what you were looking for?