Hello all,
After driving the Q45 for a while I have noticed that the overdrive doesn't work. Nothing happens when I press the button on the shifter. I still need to do a trans fluid change, any thought on if that may help or what the problem may be. The trans seems to shift fine otherwise.

Thanks

If it were me, with something like that I'd take it straight to the Infiniti dealer.

Is the car fully warmed up when you experience this? If not, many Nissan's lock out overdrive until the ECU or perhaps an internal sensor in the AT sees normal operating temperature.

Yep, tried OD on the freeway and around town at normal temps and speeds from 40 - 70 mph.

Does the O/D OFF light at bottom of PRND21 stack on the dash follow the button? So does it illuminate at all? or stay on (meaning O/D OFF) all the time, or does the indicator switch with the switch?

The OD light comes on for a second or two at startup and then goes out and never lights no matter what state the button on the shifter is in.

Hmmm- Heath had a good idea about the fluid temp sensor, but the switch/light non-correlation pretty much says it's something else. the 2 sec with key ON,engine OFF says the fuse and bulb are good.
I would probe pin 39 of the trans control unit with a DVM as you push the switch and see what you get. could be a bad ground (short or no ground).
You might also try the self-diagnostic procedure (page AT-23 of the FSM if you have no scan tool).

Anyway low trans fluid may cause this?

I was assuming you had already ruled out the obvious stuff.
The first diagnostic I had you do with indicator light vs. switch position points us to something in the control circuitry. Could be the switch, could be the TCU, could be something different.
but the indicator light should track the switch and if it doesn't, this is a clue.

Sorry, I got the car with a missing trans dipstick and its a discontinued part and there is no after market part for it. Found a few at bone yards but none near me. Finally found one at a yard by a family member lives by and they were able to pick it up and ship it. Still waiting for it.