ok sorry i have been lazy with this issue.
did some checking,15.3volts @ batt and alt. when idleing. also when ideling 10.5-11 volts @ the alt. term that goes to the PCM pin#20 which is the green wire. the other dark blue wire on the alt. puts out 14.36volts also @ idle.
also at idle on PCM pin#3 which is direct batt. feed i am getting 14.5 volts.
i hope this is enough info. thank you

 

An alternator needs to be grounded to work properly. Are you sure that yours is? I have seen applications that we had to run a ground from one of the alternator case bolts to a good engine ground.

 

yes it is grounded, when i was checking things out i grounded my meter on the case of it. also it has a 6awg cable from the factory to the block/block to battery neg. thank you

 

It sounds like the computer is energizing the alternators field when it shouldn't. With all that you have done I would head to the junkyard and pickup an old style voltage regulator with the plug for $10-$15 and temporarily wire it in to see if that cures the problem. If it does wire it in permanently. This will tell you if the problem is in the computer or not.

 

thank you seal, next weekend i will try that. i was wishing i would figure it out to repair it the proper way. if i do it with the old style voltage reg. i heard there i is a way to keep the check engine light off?? do you or anyone what that is?? thank you

 

Maybe not the best solution but you could always put a switch in the wire that feeds the check engine light. That would allow you turn the light on any time you want to check for actual codes periodically or when you have a problem without having it lit constantly.

 

hey seal, one more question. i went out and just put the key forward,in the on position,and checked for power at the small term on the alt.(the blue wire) i had nothing. does it only get power during crank and run??
all the info i have seen says it is a ignition switched power feed,so does this mean it should have power with the key in the on position?? thank you

 

Unless I am misunderstanding something, the ignition switches run position is the on position or are you talking about the accessory position. The blue wire on the alternator is normally fed from the J2 splice that is fed from the run position in the ignition switch. The J2 splice is not hot in the start position and neither is the blue wire on the alternator.

 

thanks seal that is what i found just a little bit ago.

 

i just went out and bought all the parts i need to hook up the external voltage regulator,i may get to do it this coming saturday. i still have been doing a lot of searching around for info on this issue,the proper way to resolve it.
i personally think its a bad ignition switch. why i think this is because it could have high resistance in the run position which is the keyed 12volt power source for the alternator field. the keyed 12 volt power source for the alt. field comes from the ASD relay. it also goes to the injectors,(i was also having an issue with it cranking a lot to get started,like there was no fuel,i thought it was the fuel pressure regulator,changed that to)
everything in these computer controlled trucks is a real pain,so many differant parts play a role with each other to make it all work.
my old 78 d150 years ago was so much easier.
maybe some day i will scrap all the computer crap and just run electronic ignition and a 4bbl. carb. thank you (SEAL your a big help thanks)