03FX4604

Ok so tonight driving my truck my battery light comes on. I switch the gauge on my edge to battery voltage, and it reads 12.1 while running. I get home fine and hook up my trickle charger and start it. Same thing.

So battery lights on, but the gauge hasn't moved and the truck starts runs fine.
Battery is only a year old.

I'm thinking alternator cause the battery voltage doesn't go back up when gassing the truck.

BrowningSCrew

That's probably what it is, it's what mine was.

P-Kidd

Mine just did that. The battery wasnt charging and went from 14.3 v to 8 v and died. My alternator and battery were bad.

Tackle

Battery light means alternator is not performing as it should.

Tanner2

+1 for alternator. It is on its way out!

akdoggie

You alternator is bad. The regulator is built into these. It is changeable, but you will find the armature is gouged where the brushes ran, so you will need the alternator assy to replace what you have. 12.1 volts running will drop down your battery in no time. Your output should be 13.7 or higher when running to keep a 12v battery charged. Your engine and electrical usage require that kind of replacement to keep up. Good luck.

03FX4604

Ya it's the alternator I'm picking a new one up tomorrow, get to drive my dads 08 powerstroke till then so I'm not complaining?