J'avais pas vu que tu avais trouvé la réponse  
 Doctissimo
Pour ma part, j'ai également vu sur RX8club qu'il existe différentes fonctions de diagnostiques accessibles par de petites manipulations : Test de l'instrumentation des compteurs, des hauts parleurs, des affichages radio, climatisations, etc.
http://www.rx8club.com/showthread.php?t=155947
 Diagnostic Outputs
Here are some random diagnostic outputs to use while troubleshooting.
Let me know if I missed any outputs that can be useful and I'll update this post.
Instrument Cluster:
   - Put the key in the ignition :mettre la clé de contact 
 
   - Push and hold the odometer button : appuyer sur le bouton de reset du TRIP
 
   - Turn the key to the 'ON' position (do not start the car)
 
   - Continue to hold the odometer button until 'test' appears in the lower right corner
 
   - Once 'test' appears, you can release the button
 
   - Now push (not hold) the odometer button to scroll through various numbered options
 
   - Stop when you reach the desired output
 
   - After a full second the output signal should toggle (ex: light illuminates, gauge sweeps)
          * Some have an on/off switch (ex: Buckle switch changes state when the seat belt is buckled) 
   - To exit from the output diagnostic, simply turn the key to the 'off' position and back on.
 
Here is a list of all the outputs and what they mean:
01 = Buckle switch
04 = Door switch
08 = TNS relay
12 = Speedometer
13 = Tachometer
14 = Buzzer
16 = Fuel-level warning light
18 = Ignition key illumination
22 = Fuel gauge sender unit
23 = Fuel gauge
25 = Water temperature gauge
26 = Odometer tripmeter, warning and indicator light
28 = Oil pressure gauge
31 = Key reminder switch
55 = Dimmer switch
Speaker Inspection (Test Tone)
   - With the audio power on, press the 'POWER' button and simultaneously press the 'AUTO-M' button for roughly 1 second.
 
   - It will generate a test tone in the following order:
      1st- Front driver-side door speaker and tweeter.
      2nd- Front passenger-side door speaker and tweeter.
      3rd- Driver-side rear speaker.
      4th- Passenger-side rear speaker. 
LCD Inspection:
   - With the audio power on, press the ‘POWER’ button and simultaneously press the ‘SEEK’ button for approximately 1 second
 
   - All the LCDs will illuminate. Inspect for any bad characters.
 
   - Turn the audio off or the ignition switch to the ‘LOCK’ position to stop the diagnostic assist function.
 
Button Inspection:
   - With the audio power on, press the ‘POWER’ button and simultaneously press the ‘CLOCK’ button for approximately 1 second
 
   - Press all the buttons. A buzzer sounds with each button pressed.
 
   - Turn the audio off or the ignition switch to the ‘LOCK’ position to stop the diagnostic assist function.
 
Temperature Control Knob:
   - With the audio power on, press the ‘POWER’ button and simultaneously press the ‘SCAN-UP’ button for approximately 1 second
 
   - "A/C TEMP" should appear on the left side of the LCD display and a number from 0 to 16 on the right.
 
   - The number advances in increments of 1 as you turn the temperature control knob
 
   - Turn the audio off or the ignition switch to the ‘LOCK’ position to stop the diagnostic assist function.
 
Radio Reception Condition Inspection:
   - With the audio power on, press the ‘POWER’ button and simultaneously press the ‘PRESET 2’ button for approximately 1 second.
          * Even if the system is normal, radio reception may be difficult depending on where the system is inspected (indoors/outdoors, or conditions at the location). Before inspecting the system, verify that radio reception is adequate
          * When inspecting, select a frequency band (radio station) with the best reception
            LEV- 5 through LEV- 9 = Antenna, antenna feeder and base unit are normal
            LEV- 3 through LEV- 4 = Change the frequency (radio station) and inspect again
            LEV- 0 through LEV- 2 = Malfunction present 
   - Turn the audio off or the ignition switch to the ‘LOCK’ position to stop the diagnostic assist function.
 
On-Board Diagnostic (Audio)
   - Turn the ignition to the ‘ACC’ or ‘ON’ position
 
   - While pressing the ‘POWER’ button, simultaneously press the ‘AM’ button and the ‘TAPE/MD’ button for 2 seconds or more
          * If several DTCs are in memory, they can display using the ‘SEEK’ button
          * If no DTC is stored, no codes will be displayed 
   - To stop the on-board diagnostic test mode, turn the ignition switch to the 'LOCK' position
 
Identify the device and supplier codes by referring to the LCD display.
.1 09: ER20
|__|_______|
Supplier..Device...........DTC
Supplier Code:
1 = FMS audio
2 = Panasonic
3 = CLARION
Device code:
00 = Cassette Deck
03 = CD player
05 = CD Changer (external)
06 = CD Changer (upper module)
07 = MD player
09 = Base Unit
10 = CD player system MP3 operation
Memory Clearing Procedure
- Start the on-board diagnostic test more
 
- While pressing the ‘POWER’ button, simultaneously press the ‘AUDIO CONT’ button for 2 seconds or more.
 
- To stop the on-board diagnostic test mode, turn the ignition switch to the ‘LOCK’ position
 
DTC Table (Audio System)
09: Er22 = Base unit (peripheral circuit for tuner)
09: Er20 = Power supply circuit to base unit
00: Er10 = Cassette deck communication circuit system
03: Er10 = CD player communication circuit system
05: Er10 = CD changer (external) communication circuit system
06: Er10 = CD changer (upper module) communication circuit system
07: Er10 = MD player communication circuit system
03: Er01 = CD player system
03: Er02 = CD player system
03: Er07 = CD player system
00: Er01 = Cassette deck system
00: Er03 = Cassette deck system
00: Er04 = Cassette tape system
05: Er01 = CD changer (external) system
05: Er07 = CD changer (external) system
06: Er01 = CD changer (upper module) system
06: Er02 = CD changer (upper module) system
06: Er07 = CD changer (upper module) system
07: Er01 = MD player system
07: Er02 = MD player system
07: Er07 = MD player system
07: Er08 = MD system
10: Er01 = CD player system MP3 operation
10: Er02 = CD player system MP3 operation
no Er = No DTCs stored
Immobilizer System (DTC Inspection)
   - Turn the ignition switch to the ‘ON’ position
 
   - Verify the security light state.
          * If there are any malfunctions:
                o After any malfunction is detected, the security light will function as follows for approximately 1 min.
                  DTC 16 and lower: Flashes
                  DTC21 and higher: Illuminates
          * If there are no malfunctions:
                o The security light illuminates for approximately 3 seconds and goes out. 
   - When any malfunction has been detected, read DTCs via flashing patterns displayed after the security light flashes or illuminates for approximately 1 minute.
          * A verified DTC is flashed 10 times repeatedly by the security light.
          * If multiple DTCs are verified, the security light displays only the smallest DTC. 
DTC Table (Immobilizer System)
Security light flash pattern:
∩∩_______ = No detected communication with the coil
∩∩∩______ = Coil malfunction
∩∩∩∩_____ = The key ID number data cannot be read or key ID registration error
∩∩∩∩∩____ = The keyless control module cannot read key ID number data normally
∩∩∩∩∩∩___ = The keyless control module has detected unregistered key ID number
∩∩∩∩∩∩∩__ = Communication error between the keyless control module and the PCM (no response or mismatched conditions)
∩∩∩____= Only one key ID number is registered
∩∩∩∩______ = Communication error between the keyless control module and the PCM (data transfer error)
∩∩∩∩∩____ = ID number data in the PCM and the keyless control module do not match.
NOT ILLUMINATED = Keyless control module malfunction