This is on a friends car.
1997 Talon esi 420A automatic
I swapped in a used transmission 1-3 work good, so its not in limp mode just no overdrive.
The overdrive off light doesn't come on, on the dash.
I tested the overdrive button and it is working.
But I'm not getting voltage at the orange and black wire.(on the over drive button plug)
I have checked fuses and the eatx relay.
No CEL
Is this a TCU issue?

Make sure the od button is plugged in before you jump to conclusions.
Otherwise the end clutches are smoked,Bad wire, or a solenoid is bad.
I thought end clutches at first, cause that's overdrive.
.

The o/d button is plugged in under the center console.
I checked out the wiring everything looks good.
I'm going to research on testing the solenoid pack I guess.
I'm hoping its not the end clutches.
Thanks for the reply!

The end clutches can be replaced with trans in the car. So it's not the end of the world.