2005 tundra, 4.7, daylight running lights.

My dad's buddy quickly tried to wire up a trailer to my dad's truck and wired it wrong.

7 pin connector, only the running lights were connected and instead of hooking up the ground, the trailer ground was connected to the center pin (reverse lights). Running lights were working like this. Probably not when in reverse...

http://www.etrailer.com/Merchant2/gr...043_ss_500.jpg

So he drove for a couple of hours until the truck died due to no voltage. ABS light came on and shortly after no juice and truck wouldn't start. Tow truck charged him and verified his alt was not outputting voltage.

I'm looking at the wiring diagram here.
http://www.ncttora.com/fsm/04-06-Tun...a/h/em00q3.pdf

There's three pins at the alternator connector. (one blank)

From the measurements I just took:
one has constant 12v. This must be the wire the regulator uses to sense voltage.
One has 12v when ignition is on. I assume this is 2d because the volt gauge on the dash works.

Third pin has 0v always (4d). I believe this should be 12v when ignition is on. This is the circuit: 5A ign fuse -> combination meter -> J12 connector (where it branches off to Daylight running lights) -> J26 junction connector -> eb2 -> alternator. That's following the diagram in the pdf I downloaded.

Any suggestions as to what could have happened? From what I can tell, the alternator is fine but not turning on because it's missing the signal from 4D.

The Daylight running lights are working fine and the IGN fuse is good. From the diagram, there's no other pieces in the circuit that could fail, except at the connector itself.

I don't have access to the truck tonight anymore, but looking at the diagrams, I should be able to access the connector EB2 (by the battery). I should be able to apply battery voltage to all three pins and the alternator should start charging as a test if I am reading this diagram correctly.

Thanks very much!