GM Service Manual Online
For 1990-2009 cars only

Module Information 1

Manufacture Enable Counter (MEC): The scan tool displays the actual value for the MEC in the BCM. This information is for the assembly plant only.

Module Part Number: The scan tool displays the part number assigned to the BCM that is currently in the vehicle.

Software Design Suffix: The scan tool displays the version of the software part number in the BCM.

Software Part Number: The scan tool displays the software identification number (ID) in the BCM.

Module Information 2

Lighting Calibration Number: The scan tool displays the lighting configuration calibration part number in the BCM.

Lighting Suffix: The scan tool displays the lighting configuration identification number in the BCM.

Reminder Calibration Number: The scan tool displays the reminder warning calibration part number in the BCM.

Reminder Suffix: The scan tool displays the reminder warning identification number in the BCM.

Data

Ambient Light: The scan tool displays LIGHT when the ambient light sensor voltage is between 2.2-4.7 volts. The scan tool displays DARK when the ambient light sensor voltage is between 0.2-1.3 volts.

Ambient Light Sensor: The scan tool displays the output voltage of the ambient light sensor based on the intensity of light detected. As the light intensity increases, the sensor displayed voltage increases. In the LIGHT state, a high voltage of approximately 2.6 volts is present and the Daytime Running Lamps (DRL) will be ON unless the parking brake is SET. In the DARK state, a low voltage of approximately 0.2 volts is present and the headlamps will be ON.

Battery Voltage: The scan tool displays the battery system voltage.

Courtesy Lamp Timer: The scan tool displays the seconds left before the BCM turns the courtesy lamp relay OFF. The BCM uses this feature to control the components attached to the illuminated entry, the remote illuminated entry and the exit lighting circuits.

Dimming Potentiometer: The scan tool displays the voltage value indicating the position of the IP dimmer switch (thumbwheel). The scan tool displays 0 volts when the headlamp switch is in the AUTO position and the daytime running lamps (DRL) are ON. The scan tool displays approximately 9.3 volts when either the park lamps or the headlamps are turned ON and the dome lamp switch is in the full bright position and approximately 3.8 volts in the full dim position.

Dusk: The scan tool displays Yes or No based on the intensity of light received by the ambient light sensor.

High Beam Input: The scan tool displays the voltage in order to determine the state of the high beam headlamps switch. The scan tool displays approximately 12 volts in the low beam position and approximately 1.1 volts in the high beam position.

Inadvertent Power Timer: The scan tool displays the seconds left before the BCM turns the inadvertent power relay OFF. The BCM uses this feature to protect the battery against inadvertent battery rundown caused by components that are part of the courtesy lamp circuit. The inadvertent power relay is supplied power by the BCM for approximately 1200 seconds, or about 20 minutes, after the ignition is turned OFF.

Input 1

Psgr. Door Jamb/Door Handle Switches: The scan tool displays the position of the passenger door. The scan tool displays ACTIVE when the passenger door is open or ajar.

Drivers Door Jamb Switch: The scan tool displays the position of the drivers door. The scan tool displays ACTIVE when the drivers door is open or ajar.

Ignition 1: The scan tool displays the position of the ignition switch. The scan tool displays ACTIVE when the ignition switch is in the RUN or CRANK position.

Ignition 3: The scan tool displays the position of the ignition switch. The scan tool displays ACTIVE when the ignition switch is in the RUN position only.

Ignition Power Mode: The scan tool displays the position of the ignition switch. The scan tool displays Off, Run, Crank and Unknown. The Unknown display is when the BCM can not determine the position of the ignition switch, for example, between the OFF and RUN positions.

Key in Ignition: The scan tool displays Yes if the ignition key has been inserted into the ignition switch lock cylinder. No will be displayed if the key has been removed.

Last Remote Function Actuation (RFA) Cmd. Since Wake-Up: The scan tool displays the last RFA commanded message from the BCM. The scan tool displays None when the BCM awakens from asleep status without receiving a RFA module request from a programmed key fob. The scan tool displays Lock, Unlock, or Panic when the BCM is awake and a command is activated from the key fob to the RFA module.

Lift Glass Switch: The scan tool displays On when the liftglass release switch is pressed. It will display Off when the switch is released.

Park Brake Switch: The scan tool displays the position of the park brake pedal. The scan tool displays Set when the park brake is depressed and the park brake switch is closed. The BCM uses this data in controlling the operation of the park brake indicator, the reminder chime feature and the headlamp/DRL system.

Liftglass/Rear Gate: The scan tool displays Open if the liftglass is open or ajar. Closed will be displayed when the glass is completely closed.

Rear Door Ajar: The scan tool displays Active when a rear door is open or ajar. Inactive will be displayed when the doors are completely closed.

Remote Function Actuation (RFA) Message Since Wake-Up: The scan tool displays the last message sent to the BCM from the remote control door lock receiver.

Input 2

Auto Headlamps: The scan tool displays the status of the auto headlamps. The scan tool displays Active when the auto headlamps are ON.

Auto Headlamps Enabled: The scan tool displays the status of the auto headlamps feature. The scan tool displays Yes when the auto headlamps feature has been enable and No when they have been disabled.

Courtesy Lamp Relay: The scan tool displays the state of the courtesy lamp relay. The scan tool displays ON when the BCM commands the courtesy lamps On by providing a ground for the courtesy lamp relay.

Daytime Running Lamps: The scan tool displays the status of the daytime running lamps (DRL). The scan tool displays Active when the DRL are ON.

Dim Pot Input: The scan tool displays Active indicating the presents of the IP dimmer switch (thumb wheel) signal when the park lamps are ON.

Dome Lamp Switch: The scan tool displays the position of the dome lamp switch. The scan tool displays On when the IP dimmer switch is adjusted to the full up position, past the detent, activating the dome lamp switch.

Dome Override Switch: The scan tool displays the position of the dome override switch. The scan tool displays On when the switch is activated requesting the BCM to override the interior lighting request signals. The interior lighting can still be activated with the dome lamp switch.

Flash to Pass Switch: The scan tool displays the position of the flash to pass switch. The scan tool displays On when the switch is pulled to activate the high beams momentarily while the switch is held.

Front Fog Lamp Switch: The scan tool displays the position of the front fog lamp switch. The scan tool displays On when the front fog lamp switch is activated with the park lamps or headlamps ON.

Headlamp Relay Feedback: The scan tool displays the state of the headlamps. The scan tool displays On when the headlamp and panel dimmer switch is manually turned to the ON position. The scan tool also displays On when the switch is in the AUTO position and the ambient light sensor is in its Dark state.

Headlamp Request Switch: The scan tool displays the state of the headlamp switch. The scan tool displays Active when the headlamp switch is manually turned to the ON position.

High Beam Switch: The scan tool displays the position of the high beam switch. The scan tool displays On when the high beam switch is activated.

Interior Lamp Request: The scan tool displays Active if a interior lamp request signal has been received from the RFA module.

Left Turn Signal: The scan tool displays the position of the turn signal switch. The scan tool displays On when the left turn signal is activated. The BCM uses this data to activate the turn signal reminder chime after the vehicle has traveled 0.75 miles with the turn signal switch activated.

Park Lamps: The scan tool displays the state of the park lamps. The scan tool displays On when the park lamps are activated by the BCM or the headlamp switch.

Rear Fog Lamp Switch: The scan tool displays the position of the rear fog lamp switch. The scan tool displays On when the rear fog lamp switch is activated with the park lamps or headlamps ON.

Right Turn Signal: The scan tool displays the position of the turn signal switch. The scan tool displays On when the right turn signal is activated. The BCM uses this data to activate the turn signal reminder chime after the vehicle has traveled 0.75 miles with the turn signal switch activated.

Outputs

Courtesy Lamp Relay: The scan tool displays the commanded state of the courtesy lamp relay. The scan tool displays ON when the BCM allows the courtesy lamp relay coil to go to ground to activate the courtesy lamps.

DRL: The scan tool displays the commanded state of the DRL relay. The scan tool displays On when the BCM allows the DRL relay coil to go to ground to activate the daytime running lamps.

Dimming: The scan tool displays the state of the panel dimmer switch. The scan tool displays Active when the park lamps are ON.

Front Fog Lamp Relay: The scan tool displays the commanded state of the front fog lamp relay. The scan tool displays On when the BCM allows the front fog lamp relay to go to ground to activate the front fog lamps.

Headlamp Power Relay: The scan tool displays the commanded state of the headlamp power relay. The scan tool displays On when the BCM allows the headlamp power relay to go to ground to activate the headlamps.

Inadvertent Power Relay: The scan tool displays the commanded state of the inadvertent power relay. The scan tool displays On when the BCM allows the inadvertent power relay to go to ground. The BCM allows the component of the courtesy circuit to remain on until the BCM times it off.

Interior Lighting Mode: The scan tool displays the name of the feature which commanded the interior lights on. The scan tool displays None when the interior lights are not commanded on. The scan tool displays Interior, Illum. Entry, Exit Lighting and Remote Illum. when the respective mode commands the interior lights on.

Park Lamp Relay: The scan tool displays the commanded state of the park lamp relay. The scan tool displays On when the BCM allows the park lamp relay to go to ground to activate the park lamps.

Rear Fog Lamp Relay: The scan tool displays the commanded state of the rear fog lamp relay. The scan tool displays On when the BCM allows the rear fog lamp relay to go to ground to activate the rear fog lamps (Export Only).