My battery gauge has been fluctuating lately. If I use the turn signals, the needle goes back and forth 3-5 marks. I had AutoZone test the alternator (it is an original alternator on a 95 truck) and they said it was fine. Battery terminals were corroded, so these were cleaned up. Now the needle is jumping around when the turn signals AND the power window switch is used. It does this if the truck is running or not. Plus, every once in a while if I am at a stoplight, things go dim and the truck kind of shudders and acts like it wants to die. Then all of a sudden, it jumps back and is fine. It has never died completely and always starts up the first time.

Do you think the alternator is going bad, even though it tests okay? Anything else I need to check? Thanks!

 

Sounds like it might be a ground/electrical short to me. I have a slightly similar problem with my 89 silverado, my dash lights dim and my voltage gause drops when my left turn signal is on. I would say check for loose ground wires and corosion around them. take a wire brush to the connection spots.

 

How old is the battery? You should also do a load test on the battery. If you do a lot of stop and go driving, the battery might need a deep charge to get it back to par, that is if it passes the load test.

 

Thanks! The battery is pretty new, I'd say a year at the most. Corrosion seems likely, given the age of the vehicle. I'll start there.