I've got a 97 1500 Z71 with a 5.7L. Anyway, couple weeks ago it started going from a little over 14 on the amps down to 11 on my cluster and then it would go back to 14 within a few minutes back and forth back and forth so I went to Oreillys and they said my alt. was bad but they checked it while it was doing it so I bought another one and put it on and it does the same thing so I pulled my alt. and batt. off took them in Oreillys and load test them both and they show to be good. I've checked my cables and my frame grounds and everything seems to be good. While it was at 11 volts I used a jumper wire from my batter ground to my frame to check my ground conn. and it didn't help. I also swapped batteries just to feed my curiosity and it still does it. I'm at a loss on what to do now. Any ideas?

 

Bad Cluster? Have you checked the voltage with a meter when it's reading 11 to see if that is what it is? Also your gauge reads volts, not amps. Check battery voltage and alternator output when it drops.

 

Yeah I meant volts sorry. Yeah I used a multimeter and the cluster is reading correct. When it drops the alt output with Oreillys machine says alt. voltage low but its got an internal regulator so I don't think my old one and a new would do the same thing. I'm not sayin that ain't couldn't be the prob cause I'm sure we've all got a bad module from a parts store at one time or another. lol