Battery Light wigging out

[scottharmon]

So when I roll on the throttle and the engine is under power (not at idle) the battery turns on... so every time I have seen this its has been the alternator starting to go. So I had mine tested its fine and the batterys are fine and its not a sort so what is it? All help wanted thanks

[07lariat]

Mine did this for the first time tonight. Wtf???

[jjfx407]

I was going through a similar situation all week. I took the alternator out of the truck and had it tested. It tested fine so I then took the batteries and had them tested. Batteries tested fine. I then put everything back together and watched the volts on my CTS. Everything looked fine after the batteries were charged. Few days later battery light came on and checked the volts on my CTS. Volts were 11.5. I changed the alternator last night and I'm back to normal. Long story short, just because the alternator tested good doesn't mean it is.

[dominic350]

Possible belt slippage???

[scottharmon]

hmm ok i will try it out thanks for the help

[jjfx407]

If I were you, I would take the alternator out of the truck and have it tested by a few different auto parts stores. O'reilly, Auto Zone, Pep Boys, Etc. If any of them fail the chances are you have a bad alternator.

[jesilvas]

Bad voltage regulator could be it too.

[07lariat]

Just had mine in the shop. Turns out the brushes were worn out. Had them replaced along with the slip ring and works like a charm again. Alot cheaper then replacing the alternator!