When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Is my alternator going bad or is it something else?
So this is a new issue. I was heading to a early morning car show yesterday and the check gauges came on. The car was full of gas, Had oil pressure and wasn't hot. The Alternator gauge had dropped to roughly 10 amps it would hang out there for a little bit maybe 1-2 minutes and then jump back up to its normal 15. It did this multiple times. I tried to get some good pictures of it doing it, but I was running down the freeway. Has anyone had this happen? I read it might also be a bad ground. What are your thoughts on it?
That left needle is not measuring amps, its a voltage meter. And yes, its considerably low. What year of vehicle? GM back some years ago went to a dynamic voltage control method with their alternators to increase fuel mileage but that more or less 10 volts DC number in your picture is low, even for that GM fuel savings method.
If you see that situation again, check the DC voltage with the engine running at the battery. While you are there, flip the multimeter **** to AC volts to see if you have any alternating current diode leakage out of the alternator.- this should be a very low number around .05 volts AC and might jump a little. Maybe its a bad gauge, bad instrument panel cluster, bad alternator and far less likely, a bad PCM. Could also be a dying battery with an intermittent dead cell.
That left needle is not measuring amps, its a voltage meter. And yes, its considerably low. What year of vehicle? GM back some years ago went to a dynamic voltage control method with their alternators to increase fuel mileage but that more or less 10 volts DC number in your picture is low, even for that GM fuel savings method.
If you see that situation again, check the voltage at the battery with the engine running at the battery. While you are there, flip the multimeter **** to AC volts to see if you have any alternating current diode leakage out of the alternator.- this should be a very low number around .05 volts AC and might jump a little. Maybe its a bad gauge, bad instrument panel cluster, bad alternator and far less likely, a bad PCM. Could also be a dying battery with an intermittent dead cell.
Rick
Thanks Rick it is a 2002. This was the first time it did it and it only did it going down the road. Idling at the show or at home it was fine. I need to add the dash lights did dim a bit when the gauge dropped.
Yesterday, 07:34 AM
Is my alternator going bad or is it something else? 
