Did you have the battery disconnected when you took the wires off the alternator? If you did, the Engine Computer "lost its mind" and has to have "minimum throttle" relearned before it will know when it must be in control of idle speed. To meet the conditions for the relearn to take place, (start with a charged up battery), drive it at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals. You'll likely have to keep one foot on the gas pedal to keep it running until that relearn takes place. That seven-second coast is similar to coasting off an exit ramp, but you can do it anywhere on any highway.
A working alternator will load the engine down quite a bit and that's probably why the engine stalled. The only two things left then are the voltage regulator is dead or that terminal for the green wire in the plug is stretched or corroded. A defective regulator is the more likely of the two. By grounding that green wire at the plug, with that one test you just proved the wiring is okay for the entire rest of the circuit and the alternator is okay too. If you want to be 100 percent sure the system works, do that test again after relearning minimum throttle so the engine will stay running. Then you can see what the proper full-field test does when you ground that wire. This is a standard, very quick test done to determine whether a charging problem is the fault of the regulator or something else. I explain the procedure for Fords, GMs, and Chryslers on my web site.
The first step is to mount the new voltage regulator to the body, near the computer. The housing has to make good contact to ground it so it can't be insulated by paint or rust. If you get the regulator from a salvage yard, get the plug too with a bunch of wire. You'll see the plug has a blue and green wire. Those go to the two small terminals on the back of the alternator. Probably the best idea, to keep from butchering the original wiring, is to simply leave the black plastic block and terminals off completely for now. Leave the fat output wire bolted on. For the time being, just run the two wires from the regulator to the two small studs on the alternator. The system won't work yet because we need to connect the blue wire from the truck's harness for the power source, but I think there's an easy way to do that which doesn't involve running more wires.
To figure out which wire that is, measure the voltages on the two wires shown with arrows. First do that with the ignition switch in the "run" position but the engine off. If both terminals have 0 volts, measure them again with the engine running. One will have full battery voltage and the other one should have 0 volts. Tell me which one, by arrow color, has the voltage. Also tell me if you had to have the engine running or not to get that voltage.
Friday, March 23rd, 2012 AT 6:14 PM