I have never work on gas motor trucks but the diesels fail the wire between the asd and the pcm...
It will test good with a light but cannot carry any load. I would load test from ecm pin 51 and C on the asd, and also load test at terminal A of the asd. You can make a load tester out of an old headlight and socket, one filament is about 4 amps, both filaments is about 9. Make sure it will light both coming from the ignition switch, jumper the control side of the asd, and test it at pin 51. To not spread misinformation, diesels almost never fail the blue/yellow, they fail the green/black, pin2 to the asd, and get that wonderful no start, no buss message. You need to load test, as I know a lot of diesel guys that now own 2 good pcm/ecm because they will not listen. I will add I had a friend that had a 93 Dakota brand new that would strand him all the time, no pump, dealer installed 2 fuel pumps, the fix was a new loom back to the pump, but I do not know all the exact details, maybe a hero tech cut it.