having trouble with my charging system

[casej21]

this is on a a 93 d350. its only charging at 11.9v. battery is good only about a year old, had alternator tested at local parts house and tested good, replaced the external regulator which the PO installed with a napa unit went off the wiring diagram i found online. basically 12v ignition power to top prong on VR and then wire both prongs on VR to terminals on alternator, dont matter which one goes to which. then a ground wire from alternator to VR housing. also replaced battery terminal ends added big ground wire from block to frame and cleaned up other wire ends. what else should I be looking at?

[BobS]

Make sure that the 2 field leads in the original 93 harness are not connected to the alternator.

[JimmieD]

Like BobS said, and also make sure the external voltage regulator has a good clean, tight bare metal to bare metal connections where it attaches to body parts or firewall. On several I have added another jumper wire from VR body to vehicle sheet metal as auxiliary ground.

Also important that engine to body ground be clean bare metal to bare metal. Sometimes a battery cable can look just dandy but if you cut back the insulation a bit at connector it reveals a bunch of green corrosion all over individual wires at connector. Replace entire cable, it can't be cleaned.

[casej21]

been busy just getting back to trying and figure this out. this truck isnt my DD but been putting things off till I get this fixed. I stole another alternator off another truck i have that was is good working order last time the truck was used. took that alternator in and had it tested before i put it on. well it tested bad. I went ahead and put it on the truck anyway. its still putting out only 12 volts. took a pair of jumper cables and made a ground from the alternator and VR to the battery to check if the VR was not getting grounded. NO Change. the VR has a 12 volts igntion to the top post and the orginal field leads are disconnected. I cleaned up ground ends and surfaces to ensure good ground. Im gonna take the original alternator back and have it retested. what is the best way to test these alternators, I dont feel these parts house testing units do a good job. Am I wrong?