monday batterys went dead changed them and I noticed that the battery cables were bad so I went ahead and change them also the truck seems to be chargeing alittle high but I thought it was becouse of week batterys drove the truck today charging high kicking gen on and off alt checked out good on the bench tester have any ideas btw drops below 14v at idling when driving bout 15v

 

The voltage should be between 14.4 and 14.8 when running. Different loads will lower the voltage, especially at idle. The biggest thing I would check, is turn everything on as far as accessories, and check the voltage at 1200 rpm. This is my "redneck" alternator test. Should be within the voltages above. Colder weather will make the charging system voltage a little higher, but not a ton. Batteries should be @ 12.6v when unhooked.

 

oops it kicking the gen light off and on I can be drive around it will charge high all ofa sudden then volts will drop light will go out

 

Belt slipping? or is because the charging volts are too high? Sounds like a wiring problem or the alt has an internal short to voltage. Definately get it checked out so you don't roast your new batteries!

 

Voltage regulator is in the computer -most likely cause of your problem is Not that. Check the wiring connections at the alternator, at the battery, at the computer, and to the temperature sensor under the drivers side battery tray.
If you can catch the problem when it's bad, measure the voltage across the 2 small terminals on the alternator with a voltmeter, and compare to good.

Could be the brushes in the alternator are close to gone, and working intermittent--which causes voltage to drop and light to come on due to low voltage, but sounds like you have the opposite problem. If you have 70k or more miles on the alternator, probably time to replace it, the bearings usually don't last much longer than that either.

 

I took the alt to the rebuilder and brushes were worn out the a few of the diodes were blown just had them do a complete rebuild 90.00.but something weird happened when I changed out the alt put it all back togather got in the truck to crank it and los all power for a second or 2 then everthing came back on truck started fine and charged fine no more problem I hope I'll be able to tell more tomarrow when I pull a trailer in the morning.Thanks for the help.