GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Montana - 4WD 🢒 Vehicle Control Systems 🢒 Computer/Integrating Systems 🢒 On-Board Diagnostic Features

This vehicle is equipped with an on-board diagnostic feature capable of performing the following functions:

    • Feature Customization
    • Displaying DTC codes
    • Clearing DTC codes
    • Input/Output Diagnostics

Feature Customization Mode

The feature customization mode is used to configure the body control module (BCM) to function in various applications. The BCM can be customized to change the following vehicle functions:

    • Interior Lighting Features
    • Door Lock System
    • Keyless Entry System
    • Content Theft Deterrent System

In order to enter the feature customization mode perform the following steps:

  1. Turn the ignition switch to the LOCK position.
  2. Remove the BCM PRGRM fuse.
  3. Turn the ignition switch to the ACC position.

When entering the feature customization mode, the BCM first identifies what type of BCM is installed on the vehicle by flashing the fasten seat belts indicator and sounds the chime 2, 3 or 4 times depending on the type of BCM used on the vehicle. There are 3 different types of BCM that can be installed on the vehicle based on the vehicle option content that matches the BCM capabilities. Ensure that the BCM installed on the vehicle is compatible with all of the features on the vehicle. Refer to Body Control System Description and Operation for BCM identification.

For more information on features that can be customized, refer to Personalization Description and Operation in Personalization.

Displaying DTC Codes

The DTC codes can be displayed by entering the diagnostics mode. Clearing DTC codes and Input/Output Diagnostics are also available in the diagnostics mode.

Complete the following steps in order to enter the diagnostics mode:

  1. Turn the ignition switch to the LOCK position.
  2. Remove the BCM PRGRM fuse.
  3. Turn the ignition switch to the ACC position.
  4. Turn the ignition switch from the ACC position to the LOCK position then back to the ACC position within 1 second.

The BCM will enter the on-board diagnostic mode and flash the fasten seat belts indicator and sound the chime equal to the number of DTCs stored in the BCM memory. If no DTCs are stored, the BCM will not flash the fasten seat belts indicator or activate the chime.

The BCM flashes and sounds the first DTC with the lowest number, pauses, then continues with the next DTC until all of the DTCs are read. With a DTC 1, the BCM will only sound the chime once, and the fasten seat belts indicator may not flash. Once all of the DTCs are read, the BCM repeats this sequence 3 times.

Important: If the fasten seat belts indicator does not flash, and the chime does not sound, complete the following procedure in order to confirm that the BCM has entered the diagnostics mode:

  1. Ensure that all of the vehicle doors are closed.
  2. Open and close any vehicle door.
  3. Fasten and release the driver seat belt.
The BCM sounds the chime when receiving an input signal such as Drivers door, Passengers door opening or turning on the courtesy lights when the BCM is in the diagnostics mode. Make sure these inputs are working correctly in order to prevent a false diagnoses.

If the BCM does not sound the chime upon opening a door or turning on the courtesy lights, repeat Step 1 of Entering the diagnostics mode. If the BCM does not enter the diagnostics mode, then refer to Cannot Enter BCM Diagnostics .

Clearing DTC Codes

After entering the diagnostics mode press and hold the Unlock switch for 4 seconds. The BCM will erase all history DTC codes. If a circuit is still shorted, the BCM will immediately store a history DTC code.

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
    • Headlamp switch
    • Instrument panel (I/P) 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 switches
    • Shock sensor
    • 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 select from following test modes depending on BCM type:
    5. • 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 only.
    • Test Mode 5--Energizes the horn relay for 25 ms. BCM type 4 only.
    • Test Mode 6--Turns on the security LED indicator. BCM type 4 only.
    • Test Mode 7--Turns off the security LED indicator. BCM type 4 only.

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.