I cannot find a proper wiring diagram for the speedometer circuit. My speedometer has not worked since I had the harness out of the truck working on a different problem.

The truck has code 0500 "sensor A" circuit. I have checked so many of these plugs, starting with the trans output shaft speed sensor and followed that all the way back to the PCM C2. I also tested the circuit to the rear differential ABS sensor and that one is getting 5v where according to the pinouts in the manual I have, it's supposed to be 12v. The signal wire and the voltage wire are both passing continuity tests to the pcm harness C2 and I simply cannot find anything else to test. I don't know where the speed signal actually comes from and I don't know how it gets into the gauge cluster.

Does anybody have a real diagram that shows these components in entirety?

 

I think the speedo signal is actually generated by the left front wheel speed sensor, and fed to the PCM. The PCM then sends all the data the cluster needs over its own little network, and the cluster then moves needles and such to where they need to be.