Alternstor checks out good, all wiring is good, battery is good but it only makes 12 volts. Then when I unplug the alternator it goes to ten volts. Any ideas?

 

have you tried another battery?

 

Can't say that I have. But it reads 12.5-13 volts with nothing turned on

This is also the second time this has happened recently. Had a big alternator on the truck for a while then it quit charging so I threw the sticker back on and it worked for a while then quit charging as well

 

Id try another battery, and then if that doesnt work it has to be the alternator.

 

my buddys TBSS just wouldnt crank the other night.. head lights were nice and bright everythign worked, battery had 12.5Volts. but it would just click the starter relay.
I took a battery out of my truck and put it in there, vola, cranked right up. Battery had a dead cell in it. and wouldnt take a load.

 

It cranks fine. Just has low voltage when it's running. Tried another PCM, thinking mine might not be sending a good signal, and that didn't change anything. Had another battery hooked up and no difference.