That wire will only have power for about three seconds at initial key on, and after that, only when the engine is running.

 

The dealer said there was a wire missing in the harness that supplies the power to the trans relay. I had swapped the harness before because I went from a 5.9 to a 5.2 and the local shop said I needed to get a 5.2 harness. Apparently there is some differences in the two harnesses. So I ordered another harness from a truck that had a 5.9. I called the dealer to confirm that both trucks used the same harness. Just installed the harness and test drove the truck. No engine light and it shifts fine through all gears. Thanks for the advice on figuring out the no power to relay code before going any deeper. Cost me $100 for the dealer to recommend the harness change and another $175 for the harness. Sadly the 5.2 harness cost me $250. HeyYou, you saved me a lot of time and money on this. Thank You Thank You Thank You!

 

You are welcome.