Body Control Module - Operation

OPERATION

The Body Control Module (BCM) supplies vehicle occupants with visual and audible information and controls various vehicle functions. To provide and receive information, the BCM is interfaced to the vehicle's serial bus communications network, referred to as the Programmable Communications Interface (PCI) data bus.

This network consists of the;

- Audio system equipped with RBQ radio.
- Controller Antilock Brake (CAB)
- Electromechanical Instrument Cluster (EMIC)
- HVAC Control Module
- Occupant Restraint Controller (ORC)
- Powertrain Control Module (PCM)

The BCM is operational when battery power is supplied to the module and after the ignition is FIRST powered to RUN or the driver side exterior door handle is pressed.

The BCM provides the following features:

- Automatic Door Locks
- Battery Protection - The BCM will automatically turn off all exterior lamps after 3 minutes, and all interior lamps after 15 minutes after the ignition is turned off, if they are not turned off by the driver.
- Battery Save Mode
- BCM Diagnostic Reporting
- Chime Control
- Deck lid Release (RKE only)
- Door Entry
- Door Lock Inhibit - This feature disables the door lock functions if the key is in the ignition and either front door is ajar. Pressing the Remote Keyless Entry (RKE) lock/unlock button under these conditions result in normal lock/unlock activation.
- Exterior Lighting
- Fade to Off Interior Lamps - This feature dims the interior lighting (courtesy lamps) gradually if the BCM does not receive any new inputs that would cause the interior lamps to remain on.
- Fuel Level
- Headlamp Time Delay
- Horn
- Ignition Switch Status
- Illuminated Entry
- Interior Lighting (Courtesy/Reading Lamps)
- Power Door Virtual Locks
- Power Windows - Includes Auto Down feature
- Pulse Width Modulated Instrument Panel Dimming
- Remote Keyless Entry (RKE)
- Smart Glass
- Tire Pressure Fault Detection
- Vehicle Theft Security
- Virtual Lock Automatic Door Locks

All features on the BCM are standard except Daytime Running Lamps (DRL). The customer/dealer has the ability enable or disable the following features:

- Auto Lock Disable
- Daytime Running Lamps Enable (U.S. - Option, Canada - Enabled)
- Headlamp Delay Disable
- Power Accessory Delay Disable
- RKE Horn Chirp Disable
- RKE Optical chirp Disable
- RKE Unlock - All - one press Enable

CAUTION: Do not swap Body Control Modules between vehicles or body controller's off the shelf.

The BCM has internal diagnostic capability that assists in diagnosing the system error. When an OPEN or a SHORT circuit exists, the diagnostic tool can be used to read the BCM faults. The faults are very descriptive in identifying the appropriate feature that has faulted.

The only two faults that the BCM logs that conclude the replacement of a BCM are faults;

- # 06 - Internal BCM failure (replace BCM)
- # 31 - J1850 Internal Hardware Failure (replace BCM)

Otherwise the appropriate diagnostic procedures for each of the features should be taken when the BCM logs a fault. Refer to the proper Body Diagnostic Procedures manual.

BATTERY SAVE MODE

NORMAL OPERATING MODE
The battery save mode is enabled by performing the following:
1. Insert the key into the ignition cylinder.
2. Cycle the ignition key from OFF to ACC four times without going to the RUN position.
3. Leave the switch in the OFF position after the fourth cycle. This puts the BCM into the LEARN mode.
4. Using the drivers door lock switch, UNLOCK the power locks. A single chime and a horn chirp will tell the customer that the battery save mode is being enabled.
- VTSS may be armed before the BCM Sleep Mode starts by using the RKE or the door lock switch.
- All interior and exterior lights will be turned off.
- Accessory delay will be cancelled.
- Cycling the ignition to RUN will cancel the feature. NOTE: The customer can enter and exit the vehicle by pressing the exterior door handle, this will wake up the BCM. If the vehicle was locked, then the customer must use the RKE Unlock and then press the exterior handle again. If the ignition is NOT cycled to RUN, then the BCM will re-enable this feature.

SHIPPING MODE

NOTE: When the vehicle is shipped it will be in the Shipping Mode. The BCM will enter battery save mode immediately after it goes to sleep. This is providing the following are performed:

- Ignition Off Draw (IOD) (radio fuse on this vehicle) is pulled (this sees Radio Bus Communication Fault).
- Ignition has been cycled to RUN or ACCESSORY.
- Ignition is in LOCK (with or without the key in the ignition).
- All interior and exterior lights will be turned off
- Accessory delay will be cancelled.
- The BCM has recorded less than 50 vehicle miles).

VEHICLE START UP
If the VTSS is armed when it goes into battery save mode, it will wake up in the 15 minute lights flashing alarm mode. You must disarm the VTSS with the RKE UNLOCK button or the VTSS will start alarming whenever another monitored input is active.
1. Wake the vehicle up by pressing the Driver side exterior door handle.
2. If the door does not open, the vehicle is armed (VTA lamp will start flashing). Press the RKE unlock button and then press the exterior door handle.
3. If the VTSS is active there will be a 15 minute lights only alarm.
4. Place ignition in the RUN position (this exits Battery save mode and places the BCM in the normal powered state).