I have a 93 full size Bronco with a 302.After one week to the day the battery will go dead.It has a brand new battery and the alternator is good.Both leads are new and I can't find any bad grounds.When I check the volts at the battery when sitting I have 12.48 but when I start the engine it goes down to 12.19.Any suggestions

Asked by Sep 08, 2012 at 03:04 PM

Question type: Maintenance & Repair

6 Answers


When it's running it should be putting out around 14 or so volts. If not reading this at battery try checking it directly at the alternator. If don't have it there have it checked. If you do have it there check all connections back to bAttery. (positive and ground) hope this helps

I have 12 volts at battery.When running still have 12 volts at battery and alternator.Bench checked alternator and puts out 15 volts.Changed all positive cables and main ground.At witts end!!


Sounds like your loosing your ground from alt. to battery. With truck running check voltage from positive of battery to the outer case of the alt. if you have 14 or more volts there then you have a ground issue(place positive lead of tester on positive battery post and negative lead from tester touch the metal case of alt). If not showing 14 or more volts then swap and go from negative of battery to positive of alt. if you show the voltage this way then you have an issue on the positive side wiring. Hope this helps.


You changed all cables. Did that include the ground from the motor/block to frame/battery?

Yes I did/I just now fixed this issue!It was a resistor on the back of the instrument cluster!Who would of thunk it!!!


Glad you got it fixed

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