The interior main fuse panel is located under the steering wheel behind the trim panel that your knees always hit. Turn two screws on bottom side about two or three turns
(they will not come all the way out) and then lift panel up and out,
Apparently this is fairly common... and has a very interesting cause if your case is the usual one. It is related to the failure of your heater aux water pump
1) the "multifunction" module is failing and powering down the circuit due to "low-power" fault. you did not say if the radio works when the car is off, or if it works and fails. Do your trunk and fuel door still work with the remote? Try this - use the remote when the car is running and the radio has failed, and see if it causes the radio to come on. If it does, it is resetting the module (because voltage is applied to the opposite side of the failure when the remote is used). I never fixed mine - I just soldered a jumper across pins 12 and 14 of the module. When it chokes now I lose my interiorlamp but the radio stays on (I'll replace it someday).
2) There are TWO fuses that control the radio - one powers it when the car is OFF (twilight mode) and the other when the car is ON. If radio works with car off but not ON check those fuses again.
3) Failing heater auxillary water pump
- will cause the multifunction module to "low-power" fault the radio circuit....strange but true. "
And see this thread as well
it is not as hard to fix as it seems. The engineers that designed the electrical system must have been on cheep drugs! I had the same problem and found that a auxillery water pump on the right (passenger) side of the engine compartment, was shorted. A 12 volt motor that runs it failed, and blows a 10 amp fuse labled "CLAMP" in the fuse panel by the drivers knee. there are several fuses labled CLAMP, in that fuse box. This one powers the radio, autodoor locks(drivers side only) the high beam indicator, the map lights (only when driving!) the above mentioned coolant pump, power automatic window up and down( the push and release feature) and I think the engine fan power after key out. Replace the pump(test it first!) then a new fuse, and hopfully you are good to go! I found this without any diagram, just by common sense trouble shooting and some reading on the net. I would have never thought that anyone in their right mind would wire anything this way. The only thing this method would acomplish is to let you know something is wrong! I think a check engine light would do.