Electrical problem. Hvae replaced 3 alternators in my 2006 H3, 5 cyl, 211 C.I.D, manual trans, have checked all relays, thinking it may be PCM, any suggestions?

 

monitor the volts with digital meter.

say its 12.6 b 4 starting, it should go up to 14-15
when running and drop a little.
turn on fan or headlites. should see slight dip,then right back up.
after running mine was abt 14.

if higher consistantly, its over charging. what it yours doing??

edit,,book shows batt/generator control module along with pcm. module back of batt,fender end.

it looks like mod controls gen with duty cycle signal, not vary volts, also a gen turn on signal.

the pcm sends a gen,reg signal to the mod!!

it was simple 20 years ago!

 

Mine drops down to 12.4 and stay there. Turn on heads lights and it immediately drops and battery starts to drain. Should be 14.2 amps but never gets that high, even when battely is fully charged and hummer is running.