Battery gauge bouncing

[bouncytruck]

The battery gauge needle is bouncing side to side when the truck is at an idle or at a constant speed (bounces more at idle). I also noticed that the dash lights are dimmer when I'm sitting at a stop light than when I accelerate.

Where should I start - Battery or Alternator?

[Critter]

Internally or externally regulated? In my experience if your charging system is in good working order you should be able to remove your battery altogether, throw it in the ditch, and everything will run and perform properly. I would start by checking all the major connections i.e. cables, alternator wire, and main grounds ESPECIALLY the dash panel ground along with the body to frame, engine to frame, engine to body, whatever you may have...maybe at a couple more while you are at it, can't have to many.

EDIT: Have you taken a volt meter and checked the voltage at the battery???

[mikewayne]

But in my truck the gauge cluster is bad the mechanic told me he disconnected the fuel pump and my fuel gauge still pegs past full, although for know it returns to the correct fuel level.

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[old man jimmy]

voltage regulator kicking on & off. Try a new one.

[fixit-p]

Sounds reasonable to me that you would have a bouncy gauge in a bouncy truck








Sorry, i couldn't resist the humor in it.

Is this a volt gauge or factory ammeter, first thing I would do is verify your voltage readings with a DMM

[Pyro]

Certainly sounds like a faulty regulator to me. Take a volt meter and read the voltage at the battery while it's running. See what it's reading at idle and when revved up.