Did you try a new relay? They're cheap.You can just pull one from something else to test it to see if the OD light turns off and your high gear starts in D are gone.
Focus on restoring power to your TECA and your trans will work correctly again.
Under the hood of the 9th gen trucks,there is a power distribution box with the relay in the same location.There is a fuse that powers the relay.With your year van,I don't know where power comes from,be it either fed through a fuse somewhere also or simply a fuseable link,possibly at the fender mounted solenoid.Find this info,feed the relay power again,and you should be good.
You should be able to test for power at your relay pins as well to see if you have power this far.If so,then power is lost between the relay and the TECA.