[RPegram]

In the daytime my radio and overhead will dim so low with headlights on i can barely see them, but they are plenty bright at night. I believe you need to get the issues taken care of with the OD button and then you can move on to diagnosing the OD issue. What you are feeling as OD, could it possibly be converter lockup and not OD? Easy test is to get to highway speed, keep right foot on go pedal and keep speed steady, touch brake pedal with left foot just enough to turn on brake lights and see if RPM's change. They should go up a few hundred and drop back down a few seconds after letting off the brake. IIRC correctly, the OD button simply grounds out a wire when you push it and does nothing while not being pushed. It grounds wire again when you push it and light toggles off or resets when you turn ignition off. The converter should lock no matter if your in 3rd or OD. One other thing to check is the TPS. Here are instructions to do so:

Click > TPS testing and adjustment