Entering Input/Output Diagnostic Mode

After the BCM reads all of the DTCs in the memory, the BCM enters the Input/Output Diagnostic Mode. The BCM flashes the fasten seat belts indicator and sounds the chime once when any of the following inputs are activated:
^ Courtesy lamp switches
^ Door lock cylinder switches
^ Driver door ajar switch
^ Driver fasten seat belt switch
^ Driver Information Display (DID)
^ Headlamp switch
^ IP compartment lamp switch
^ Keyless entry request for door lock/unlock
^ Keyless entry request for the alarm (RPO UA6)
^ Passenger door ajar switch
^ Power door lock switches
^ Liftgate ajar switch
^ Sliding door ajar switch(es)
^ Shock sensor
^ Sunshade illuminated mirrors
^ Hazard switch

Perform the following procedure in order to test the BCM outputs:
1. Ensure that the BCM is in the diagnostic mode. Refer to Entering On-Board Diagnostic Mode.
2. Cycle the interior light switch ON then OFF.
3. The BCM will enter the Output Diagnostic Test Mode 1.
4. Each cycle of the interior light switch (ON/OFF) will to select from following test modes depending on BCM type:
^ Test Mode 1- De-activates the courtesy lights output and removes power to all of the interior lamps.
^ Test Mode 2- Activates the courtesy lights output and provides power to all of the interior lamps (interior lamp override switch must be ON).
^ Test Mode 3- Activates the courtesy lights output and turns ON all of the courtesy lamps (interior lamp switch must be ON).
^ Test Mode 4- Activates the theft deterrent relay for 1 second and turns ON the headlamps (BCM type 4).
^ Test Mode 5- Energizes the horn relay for 25 ms (BCM type 4).
^ Test Mode 6- Turns on the security LED indicator (BCM type 4).
^ Test Mode 7- Turns off the security LED indicator (BCM type 4).

When the BCM completes all test modes, the BCM will repeat the test mode sequence.

Exiting Diagnostics
Perform the following procedure in order to exit the BCM diagnostics mode and return to normal BCM operation:
1. Turn the ignition switch to the LOCK position.
2. Reinstall the BCM PRGRM fuse.
3. Turn the ignition switch to the RUN position.

For a description of the RPO Code(s) shown in this article, refer to the RPO Code List found at Vehicle/Application and ID. Application and ID