I got a 2012 f150 with a 5.0 xlt 4x4. The battery light came on the instrument panel and has been coming on more frequent. So i pulled the codes using forscan and one code was PO625 so took altenator to napa to get it tested. They at napa couldnt test it so it was under warranty so they gave me a new one(rebuilt) so put it on. Also noticed alot of high system voltage codes in alot of modules. New alt didnt fix battery light. So did pinpoint test from ford. So i discovered i had 11 volts on genmon wire. Unplugged wire harness from pcm and tested all three wires. None shorted to ground, not shorted together. So i pulled the wire out of connector and plug it back in to pcm and test for voltage on genmon wire and nothing. So i test it at pcm and i got 11 volts coming out of pcm terminal! It should be zero since it should be monitoring what the alt is putting out. Correct? I think the pcm is fried.

thanks

 

Welcome, our trucks are very sensitive to non Ford alternators.