Rando1

my alt gauge is pegging into positive,msd set up.all new everything,harness alt,any ideas?

rtruman

voltage regulator needs adjustment Check DC voltage at alternator and at battery posts .
see actual voltage in relation to Alt.

65GGvert

If it pegs without engine running, double check your wiring at the horn relay and at the starter wires that go to the gauge. Both wires go to 12v, neither to ground. If it's only when running, go to the regulator area.

ChattanoogaJSB

I'm not sure at all if this helps, but I almost burned down my '70 Challenger ten years ago when I rebuilt the alternator and when I reinstalled I failed to put on one small nylon insulating washer on a wire feeding the regulator...made it charge wide open, grounding that side. I never ignore a pegged gauge! The dash harness fused together, solid! Now I always carry a fire extinguisher. Good luck!

Ironcross

alternators average from 13.6 to 14.4 in the charging mode....if not or overcharging, then the regulator as suggested requires immediate attention...you could damage the 12 volt accessories if you leave it ride.....{bulbs, radio, ect}