After doing a cold start with the 737-800 in FSX how do you turn on the GPS and Radio stack? The main attitude and heading panels are on, just no the GPS and Radio stack.
It's been a while since I flew that plane.. but I seem to remember that it does not have an avionics master switch. If you start totally cold, you'll need to turn it on too.
There's a hot-key for it.. check the key assigments.