Charging system problem

I just finished an engine swap and lift kit install on my 1993 k1500 (now has an engine, tranny, computer and wiring harness out of my 1989 k1500) I went to drive my truck to the alignment shop and made it about half way there when the truck died. I should have done a few more tests before I left to prevent this, but here's the problem. I'm getting no charging from the alternator. I put a multi-meter on the battery terminals and without the engine running it showed 11.9V. With the engine running it also showed 11.9V. So, I took my alternator into the shop and they tested it and it seemed fine. I bought a new alternator anyway and installed it. Same problem. I also tested the voltage at the positive terminal on the alternator and it showed 11.9 when cold and when running. The only wires coming off the alternator are the positive terminal wire and a single wire plug that plugs in on the upper right side, I assume for the internal voltage regulator. So, I'm kind of stuck. Could be something really stupid. Any ideas? Thanks guys-

All grounds on

Yeah, all the grounds are on and everything else seems to be functioning fine. I did a bit of troubleshooting last night and found out a few things. The problem lies in the single brown wire that comes and plug's into the alternator. I believe this wire is a signal wire that tells the alternator when the ignition is turned on. When I provided a positive signal to this wire with the engine already running, the alternator started producing 14.6V Now I just have a few questions. Does this wire serve any function other than to provide a positive signal when the ignition is on? Is it constantly or only a momentary pulse when the key is first turned? Does anyone have a wiring diagram for the 1993 k1500? If I had this I could trace the wqire that serves the same function and see what it's supposed to be doing and patch them together. I got most of my wiring info for this out of a Chilton's manual for the 1989. It had a diagram on the charging system that showed the alternator. Thanks for your help everyone-

Yeah, all the grounds are on and everything else seems to be functioning fine. I did a bit of troubleshooting last night and found out a few things. The problem lies in the single brown wire that comes and plug's into the alternator. I believe this wire is a signal wire that tells the alternator when the ignition is turned on. When I provided a positive signal to this wire with the engine already running, the alternator started producing 14.6V Now I just have a few questions. Does this wire serve any function other than to provide a positive signal when the ignition is on? Is it constantly or only a momentary pulse when the key is first turned? Does anyone have a wiring diagram for the 1993 k1500? If I had this I could trace the wqire that serves the same function and see what it's supposed to be doing and patch them together. I got most of my wiring info for this out of a Chilton's manual for the 1989. It had a diagram on the charging system that showed the alternator. Thanks for your help everyone-

I have the wiring diagram, I just sent a copy to Broughty84, I have it on paperback old manual so I sent it "real mail" not e-mail. The brown wire is for the voltage gauge and it plugs into voltage regulator on alternator, thrers something im missing, (going on just memory here, my manuals are packed away) ask broughty84 he just fixed his.

Thanks Skipr, I sen't broughty84 an email, so hopefully he'll have time to help out. I think that the wire is just a different color or in a different location in the 1993 and for some reason it isn't getting the signal to the alternator. Maybe just a difference in the main plugs. Thanks for your help-