My 2004 RX8 ignition light is on indicating a possible electronics problem. The door lock, the interior and trunk lights are not working. . the radio/CD player does not work and the radio panel,

Door ajar switch problem more then likely or wiring issue . The BCM - body control module won't turn off interior light , let door lock because it think's the door is open . The door ajar switch is a input to the BCM .

The first thing would be to have it checked for DTC'S - diagnostic trouble codes . Also check with an enhanced scan tool to see if the BCM shows ajar switch data (open or closed ? Do you know about body electronics ?
Body Control Module
The various BCM input and output circuits are described in the corresponding functional areas indicated on the BCM electrical schematics. The Body Control Module functions include the following:
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A/C compressor request. Refer to Air Temperature Description and Operation

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Remote Function Control. Refer to Keyless Entry System Description and Operation

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A/C cooling Fan. Refer to Air Delivery Description and Operation

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Audio Delay Power. Refer to Radio/Audio System Description and Operation

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Exterior and interior lighting control. Refer to Exterior Lighting Systems Description and Operation

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Daytime running lights (DRL)

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Automatic lighting control

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Fog lamps

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Interior lighting. Refer to Interior Lighting Systems Description and Operation

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Battery rundown protection (Inadvertent Power). Refer to Interior Lighting Systems Description and Operation

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Chimes. Refer to Audible Warnings Description and Operation

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Key-In-Ignition

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Head Lamps On

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Seat Belt Not Fastened

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Turn Signal On

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Park Brake Warning

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Door Ajar Warning

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Check gages

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Gage control. Refer to Instrument Cluster Description and Operation in Instrument Panel, Gages, and Console.

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Instrument cluster indicator control. Refer to Instrument Cluster Description and Operation in Instrument Panel, Gages, and Console.

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Theft deterrent. Refer to Theft Systems Description and Operation .

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Engine coolant level sensing. Refer to Cooling System Description and Operation .

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Washer solvent level sensing. Refer to Wiper/Washer System Description and Operation in Wipers/Washer Systems.

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Key-in-ignition sensing. Refer to Audible Warnings Description and Operation in Instrument Panel, Gages, and Console.

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Seat belt use sensing. Refer to Seat Belt System Description and Operation .

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Brake fluid level sensing.

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Parking brake state sensing.

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Rear compartment interface. Refer to Power Door Locks Description and Operation

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Horn interface.

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Door lock interface. Refer to Power Door Locks Description and Operation

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Bulb Check. Refer to Instrument Cluster Description and Operation in Instrument Panel, Gages, and Console.

one of the door switches is sticking, try spraying PBlaster in all doors top and bottom of the latches, and trunk/decklid.........

This is not a good thing. Ford uses a computer called the GEM and that means General Electronics Module. It controls:

• Low Coolant Indicator On Cluster
• Brake Indicator on Cluster
• DRL - Control
• Wipers
• AutoLamps
• Rear Defrost
• Interior Lamps(dome)
• High Beam Indicator only (cluster)
• Low Coolant indicator
• Key-in Buzzer
• Seatbelt indicator only (Cluster)
• Trunk Pop Relay
• Power Locks
• Door Ajar Sensors
• Door Keyless entry pad
• Remote Keyless Entry
• One Touch Down (power window)
• Air Bag Tone
• Anti Theft (perimeter Alarm) (SEL, or SE(s) with mods)
• Lift gate ajar (wagon)
• Liftgate Pop
• Accessory Delay signal (accessory that work after engine off, prior to door ajar)
• Battery Saver Relay signal (accessory that work after engine off, 15 mins) Map lights, vanity mirrors

They are located behind the radio in the dash and they are $$$ about 600 USD.

have you checked the fuzes ?

Sounds very much like two possibles a short in the fuse box to the non working parts or your battery went dead and was recharged and you did not reset these items. As what U mention all sound like the equipment that needs to be reset when you change a battery or it goes dead.

2003 MPV. Room Fuse would immediately blow when replaced - as a result, no audio, auto doors, interior lights, etc. It would blow without the key in the ignition so I knew it had to be something that operated without the electric being turned on. Started guessing by pulling the fuses for the auto doors then retrying the Room Fuse.. Room Fuse continued to blow. Then went through interior lighting - started taking out bulbs and disconnecting lighting connections trying to isolate the issue.. popped the visor mirrors out and noticed one of the connections had come loose.. reconnected, popped in another Room Fuse, and presto! Everything back to normal - lucky me.

security module in the trunk ???? There is no security module in the trunk . What light's come on by them self ? Park lamps , headlamps , brake lamps ,turn signals etc.... The module for anti-theft is under the right hand side of the dash . The remote keyless entry module is located in the trunk. Is this the part you hear clicking in ?
Door Lock Control Processor, Electronic NOTE: The electronic door lock control system will not function when the ignition switch is in the RUN or ACC position.
The electronic door lock control processor:

• is located on the LH side of the luggage compartment.
• contains a radio receiver that receives a signal from the keyless entry remote transmitter (15K601) through electronic door lock control processor antenna, and sends the appropriate command to the power door locks, the horn relay, the indicator flasher, or the anti-theft warning system.
• is equipped with a battery backup which holds the programmed code in memory in the event the vehicle battery is disconnected.
• • Doors Do Not Lock or Unlock Using Keyless Entry Remote Transmitter
  • Circuit.
  • Electronic door lock control processor.
  • Keyless entry remote transmitter.
  • GO to Pinpoint Test B .

This sounds like a security issue. Look into your manual to see about resetting it.

check fusebox you may have blown the fuse

2004 Rx8 kept blowing 15amp brake light fuse. Solution: wire going to rear lights was worn and frayed where it feeds through the left trunk lip on left side of trunk. This can be seen when you open the trunk lid. The wire routes by the trunk lid hinge. If the support connectors come loose, the wires are crunched by the hinge or lid. Re-splice, insulate, zip-tie, replace fuse and replace any blown bulbs.