Computer/integrating Systems: Other Chevrolet Uplander I

Body Control Module (BCM) C2

Computer/Integrating Systems Connector End Views

Body Control Module (BCM) C2

Scheme 10

Computer/Integrating Systems Connector End Views

Body Control Module (BCM) C3

Scheme 11

Computer/Integrating Systems Connector End Views

Data Link Connector (DLC)

Conditions for Setting the DTCs

1. No valid messages are detected on the class 2 serial data circuit.
2. The voltage level detected on the class 2 serial data circuit is in one of the following conditions: High Low
3. The above conditions are met for approximately 3 seconds.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Retained Accessory Power (RAP) Inoperative

Retained Accessory Power (RAP) Inoperative

Control Module References

Control Module References

Body Control Module (BCM) Programming/RPO Configuration

A new body control module (BCM) must be programmed with the proper RPO configurations. The BCM stores the information regarding the vehicle options and if the BCM is not properly configured with the correct RPO codes, the BCM will not control all of the features properly. The Tech 2 software will automatically prompt you with the possible RPO's available for the vehicle. Ensure that the following conditions exist and are met in order to prepare for BCM programming

1. Understand this entire procedure.
2. The battery is fully charged.
3. The ignition switch is in the ON position.
4. The data link connector (DLC) is accessible.
5. All disconnected modules and devices are reconnected before programming.
6. Follow all Scan Tool on screen directions.
7. Take time to verify the VIN on the Scan Tool is correct, failure to do this could result in the service part being made unprogrammable.

BCM Setup

1. To setup a new BCM, navigate to the Module Setup menu in Computer Integrating Systems on the scan tool, select Body Control Module.
2. Run the BCM Setup, BPP Calibration and Program Key Fobs procedures.
3. If the BCM fails to accept the program, perform the following steps: Inspect all BCM connections. Verify that the scan tool has the latest software version.

Remote Start Programming

The Remote Start option can only be programmed with an SPS terminal and a Scan tool configured in the Pass Thru programming arrangement. Use this arrangement and select Remote Start setup on the SPS terminal once the programming options appear. Choose the appropriate settings when prompted for engaging or disengaging the Remote Start option. Refer to BODY CONTROL MODULE PROGRAMMING AND SETUP in Programming and Setup for the proper procedure.

Passkey 3 Programming Procedures

Perform the Passkey 3/VTD Programming Procedure if any of the following components have been replaced

1. The BCM
2. The powertrain control module (PCM)
3. Passkey sensor.

Refer to Programming Theft Deterrent System Components in Theft Deterrent for the programming procedure.

1. Turn the ignition OFF for 10 seconds.
2. Connect the scan tool to the data link connector.
3. Turn the ignition ON with the engine OFF.
4. Use the scan tool in order to retrieve history DTCs from all modules.
5. Clear all history DTCs.

Data Link Connector (DLC)

The data link connector (DLC) is a standardized 16-way connector located below the instrument panel and close to the steering column. Both the connector design and location are dictated by industry wide agreement to follow SAE J1962 standards.

All DLCs are required to provide a power supply, hot at all times, to Pin 16. This circuit is used to power the scan tool. All DLCs provide a power ground at Pin 4 and a clean signal ground at Pin 5.

The class 2 serial data communications circuit is provided at Pin 2 of the DLC.

Class 2 Serial Data Link

The class 2 serial data link allows the following modules to communicate and share data with each other

1. Body control module (BCM)
2. Digital radio receiver (DRR)
3. Driver information center (DIC)
4. Digital video disk (DVD)
5. Electronic brake control module (EBCM)
6. Instrument panel cluster (IPC)
7. Head up display (HUD)
8. HVAC module
9. Left hand power sliding door module (LHPSDM)
10. Memory seat module (MSM)
11. Powertrain control module (PCM)
12. Radio
13. Right hand power sliding door module (RHPSDM)
14. Inflatable restraint sensing and diagnostic module (SDM)
15. Vehicle control interface module (VCIM)

The class 2 serial data link allows a scan tool to communicate with the above modules for diagnostic and testing purposes.

Power Mode Master

This vehicles BCM functions as the Power Mode Master (PMM). Refer to Power Mode Description and Operation for a complete description of the power mode functions.

Body Control Module

The various body control module (BCM) input and output circuits are described in the corresponding functional areas indicated on the BCM electrical schematics. The BCM functions include the following

1. Battery rundown protection-Inadvertent power-Refer to «Interior Lighting Systems Description and Operation»(ref-241674-S06473241032006081100000) in Lighting Systems.
2. BTSI/automatic transmission shift lock control-Refer to «Automatic Transmission Shift Lock Control Description and Operation»(ref-241731-S03304192092006081100000) in Automatic Transaxle - 4T65-E.
3. Bulb check-Refer to «Instrument Panel Cluster (IPC) Description and Operation»(ref-241678-S10070739852006081100000) in Instrument Panel, Gages and Console.
4. Chimes-Refer to «Audible Warnings Description and Operation»(ref-241678-S00693305072006081100000) in Instrument Panel, Gages and Console. Check gages Content theft deterrent Door ajar warning Headlamps ON Key-in-ignition Oil reset Park brake warning Seat belt not fastened Turn signal ON Vehicle theft deterrent
5. Door lock interface-Refer to «Power Door Locks Description and Operation»(ref-241675-S20585420772006081100000) in Doors.
6. Exterior and interior lighting control-Refer to «Exterior Lighting Systems Description and Operation»(ref-241674-S30597271222006081100000) in Lighting Systems. Automatic lighting control Backup lamps Daytime running lights (DRL) Fog lamps High/low beam head lamps Park brake lights Turn hazard lamps
7. Gage control-Refer to «Instrument Panel Cluster (IPC) Description and Operation»(ref-241678-S10070739852006081100000) in Instrument Panel, Gages and Console.
8. Heated seats-Refer to «Heated Seats Description and Operation»(ref-241729-S16992471852006081100000) in Seats.
9. Horn interface-Refer to «Horns System Description and Operation»(ref-241673-S16097291542006081100000) in Horns.
10. Instrument cluster indicator control-Refer to «Instrument Panel Cluster (IPC) Description and Operation»(ref-241678-S10070739852006081100000) in Instrument Panel, Gages and Console.
11. Interior lighting-Refer to «Interior Lighting Systems Description and Operation»(ref-241674-S06473241032006081100000) in Lighting Systems.
12. Key-in-ignition sensing-Refer to «Audible Warnings Description and Operation»(ref-241678-S00693305072006081100000) in Instrument Panel, Gages and Console.
13. Parking brake state sensing-Refer to «Brake Warning System Description and Operation»(ref-241721-S08350857322006081100000) in Hydraulic Brakes.
14. Retained accessory power (RAP)- Refer to «Retained Accessory Power (RAP) Description and Operation»(ref-241672-S19729951882006081100000) in Retained Accessory Power.
15. Rear compartment interface-Refer to «Power Door Locks Description and Operation»(ref-241675-S20585420772006081100000) in Doors.
16. Rear defogger-Refer to «Rear Window Defogger Description and Operation»(ref-241702-S24958249852006081100000) in Stationary Windows.
17. Remote function control-Refer to «Keyless Entry System Description and Operation»(ref-241691-S22882930082006081100000) in Keyless Entry.
18. RFA communication link-Refer to «Keyless Entry System Description and Operation»(ref-241691-S22882930082006081100000) in Keyless Entry.
19. Seat belt use sensing-Refer to «Seat Belt System Description and Operation»(ref-241725-S26978143972006081100000) in Seat Belts.
20. Theft deterrent vehicle/content-Refer to «Theft Systems Description and Operation»(ref-241694-S14215689152006081100000) in Theft Deterrent.
21. Washer solvent level sensing-Refer to «Wiper/Washer System Description and Operation»(ref-241701-S29947012252006081100000) in Wipers/Washer Systems.
22. Wiper/washer-Refer to «Wiper/Washer System Description and Operation»(ref-241701-S29947012252006081100000) in Wipers/Washer Systems.

Serial Data Power Mode

On vehicles that have several control modules connected by serial data circuits, one module is the power mode master (PMM). On this vehicle, the PMM is the body control module (BCM). The PMM receives 3 discrete ignition switch signals to differentiate which power mode will be sent over the Serial Data circuits. The table below illustrates the state of these inputs in correspondence to the ignition switch position

3-Wire Ignition Switch Table

Relay Controlled Power Mode

The body control module (BCM) uses the discrete ignition switch inputs ignition 1, ignition 3 and crank to distinguish the correct power mode. Once the BCM has determined the power mode selected by the vehicle operator it will energize the Ignition relay, Run relay and retained accessory power (RAP) relay, depending on which power mode is selected.

Ignition 1 Relay

The relay uses a Hot At All Times B+ power source derived from the underhood electrical center. The ignition 1 relay supplies a power signal to the following circuits when the Run or Crank power mode is selected

1. AC clutch relay
2. ABS STG angle sensor
3. Antilock brake system (ABS) yaw sensor
4. Auxiliary power drop connector
5. Crank relay
6. Cruse control switch
7. Electronic brake control module (EBCM)
8. Engine control module (ECM)
9. HVAC module
10. Ignition control module (ICM)
11. Instrument panel cluster (IPC)
12. Sensing and diagnostic module (SDM)
13. Transmission solenoid circuit

Retained Accessory Power (RAP) Relay

The RAP relay is energized when the Run or Accessory power mode has been selected. The relay uses a Hot At All Times B+ power source derived from the underhood electrical center. The B+ power source is protected by the 50 Amp BATT MAIN 2 fuse. The BCM also energizes the relay for 10 minutes after the vehicle operator transitions the ignition switch from Accessory to OFF or Run to OFF positions. The following circuits are controlled by the RAP relay

1. Power sunroof
2. Power windows

Fail-Safe Operation

Since the operation of the vehicle systems depends on the power mode, there is a fail-safe plan in place should the power mode master (PMM) fail to send a power mode message. The fail-safe plan covers those modules using exclusively serial data control of power mode as well as those modules with discrete ignition signal inputs.

Serial Data Messages

The modules that depend exclusively on serial data messages for power modes stay in the state dictated by the last valid PMM message until they can check for the engine run flag status on the serial data circuits. If the PMM fails, the modules monitor the serial data circuit for the engine run flag serial data. If the engine run flag serial data is True, indicating that the engine is running, the modules fail-safe to RUN. In this state the modules and their subsystems can support all operator requirements. If the engine run flag serial data is False, indicating that the engine is not running, the modules fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

Discrete Ignition Signals

Those modules that have discrete ignition signal inputs also remain in the state dictated by the last valid PMM message received on the serial data circuits. They then check the state of their discrete ignition input to determine the current valid state. If the discrete ignition input is active, battery positive voltage, the modules will fail-safe to the RUN power mode. If the discrete ignition input is not active, open or 0 volts, the modules will fail-safe to OFF-AWAKE. In this state the modules are constantly checking for a change status message on the serial data circuits and can respond to both local inputs and serial data inputs from other modules on the vehicle.

BCM Wake-Up/Sleep States

The body control module (BCM) is able to control or perform all of the BCM functions in the wake-up state. The BCM enters the sleep state when active control or monitoring of system functions has stopped and the BCM has become idle again. The BCM must detect certain wake-up inputs before entering the wake-up state. The BCM monitors for these inputs during the sleep state, where the BCM is able to detect switch transitions that cause the BCM to wake-up when activated or deactivated. Multiple switch inputs are needed in order to sense both the insertion of the ignition key and the power mode requested. This would allow the BCM to enter a sleep state when the key is IN or OUT of the ignition.

The BCM will enter a wake-up state if any of the following wake-up inputs are detected

1. Activity on the serial data line
2. Detection of a battery disconnect and reconnect condition
3. Headlamps are ON.
4. Ignition is turned ON.
5. Key-in-ignition switch
6. Park lamps are ON.

The BCM will enter a sleep state when all of the following conditions exist

1. The ignition switch is OFF.
2. No activity exists on the serial data line.
3. No outputs are commanded.
4. No delay timers are actively counting.
5. No wake-up inputs are present.

If all these conditions are met the BCM will enter a low power or sleep condition. This condition indicates that the BCM, which is the power mode master (PMM) of the vehicle, has sent an OFF-ASLEEP message to the other systems on the serial data line.

Serial Data Control of Retained Accessory Power (RAP)

Retained accessory power (RAP) is a vehicle power mode that permits the operation of selected customer convenience items after the ignition switch is turned OFF. These selected items will remain in operation until a passenger compartment door is opened or until the RAP function timer reaches its time-out limit.

The modules listed below all receive a RAP message from the body control module (BCM) over the serial data circuits. The BCM monitors the ignition switch position, battery condition and passenger compartment door status to determine whether RAP should be initiated. The BCM then sends a message to the listed modules telling them that they are in RAP power mode. The modules then support the operation of the systems under their control as required by their RAP power mode strategy.

RAP will end when one of the following conditions are met

1. The BCM receives an input (as a hard wired input from the door switches) indicating the opening of a passenger compartment door.
2. The BCM receives a message from its internal timer indicating the end of the RAP period after 10 minutes.
3. The BCM detects a decrease in battery capacity below a prescribed limit.
4. The transition from OFF to RUN/ON or ACC of the ignition switch.

The BCM then sends a serial data message to the listed devices ending the RAP function.

The devices receiving serial data messages for RAP functions are

1. Driver information center (DIC)
2. Digital radio receiver (DRR), if equipped
3. Head up display (HUD)
4. Instrument panel cluster (IPC)
5. Radio
6. Vehicle communication interface module (VCIM), if equipped

Relay Control of Retained Accessory Power (RAP)

Retained accessory power (RAP) is a vehicle power mode that permits the operation of selected customer convenience items after the ignition switch is turned OFF. These selected items will remain in operation until a passenger compartment door is opened or until the RAP function timer reaches its time-out limit.

The body control module (BCM) activates the RAP relay in either the RAP function as described above or if the BCM detects a RUN/ON or accessory power mode. This provides power for the following

1. The power windows
2. The sunroof control module, if equipped

The BCM deactivates the RAP relay to end the RAP function when it ends the RAP function as outlined in the previous text.