I got it charging by accident.....I have a test light that hooks to your battery both pos and neg,with green and red light. I just started testing wires behind starter solenoid. I lightly poked the one that comes from the alternator (green and red stripe) and it started charging......shut the truck off checked voltage and it starts dropping repoke the wire starts charging and holds steady,turn headlights heater on stays charging...now I'm not sure but I think it is not grounded or it needs power.....any ideas or what the heck is going on.thanks for your input....

 

pls check wiring

 

At this point we know the alt is good, even though store tests are not that reliable.
You need to answer my question of whether or not the voltage regulator is integral with the alternator or is mounted separately.
If the regulator is mounted separately it may be defective ,or have a poor connection.
Also if separately, we jump the "A" terminal with the "F" terminal locations in the regulator plug with it unplugged from the regulator. That by passes the regulator and confirms condition. If charging takes place with the terminals jumped, replace the regulator.

 

It is a internal regulator. the top plug which is the regulator has 3 wires the green with red stripe yellow and a white with white stripe. I grounded the green one and it started charging.

 

If you happen to have a copy of the owner's manual, check which fuse supplies the alt field. If no copy . use the test light , with clip connected to a good ground and the key on , check both sides of each fuse. The one that supplies the alt will lite on one end of the fuse and not the other. If you find that to be the problem, just replace the fuse and that should make power available to the alt control circuit.