Action Taken When the DTCs Sets
- The module suspends all message transmission.
- The module uses default values for all parameters received on the serial data circuits.
- The module inhibits the setting of all other communication DTCs.
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) On After Timeout
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Retained Accessory Power (RAP) Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Do only the devices powered by the accessory relay exhibit this symptom? | Go to Step 4 | Go to Step 3 |
| 3 | Install a scan tool. Select body control module (BCM) data in data display. Close all the doors. Turn ON the ignition, with the engine OFF. Wait 5 seconds, then turn the ignition OFF. Wait for the retained accessory power (RAP) time-out. Does the scan tool display the Accessory power mode, then time-out, and display Off-Awake or OFF power mode? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 10 |
| 4 | Turn the ignition switch to the OFF position. Disconnect the accessory relay. Do the devices controlled by the Accessory relay operate? | Go to Step 5 | Go to Step 6 |
| 5 | Repair the short to battery in the accessory relay switched output circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 12 | |
| 6 | Open the driver door. Connect a test lamp across the relay coil circuits of the Accessory relay socket. Does the test lamp illuminate? | Go to Step 7 | Go to Step 8 |
| 7 | Test the accessory relay control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
| 8 | Inspect for poor connections at the accessory relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 |
| 9 | Replace the accessory relay. Did you complete the replacement? | Go to Step 12 | |
| 10 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
| 11 | IMPORTANT: Perform the module setup procedure, if required. Replace the BCM. Refer to Body Control Module Replacement .Did you complete the procedure? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
| IMPORTANT |
|---|
| Perform the module setup procedure, if required. |
Retained Accessory Power (RAP) On After Timeout
Retained Accessory Power (RAP) Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Retained Accessory Power (RAP) Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Close all of the doors. Turn ON the ignition, with the engine OFF. Turn OFF the ignition. Do all the retained accessory power (RAP) functions operate during the RAP mode? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do only the devices powered by the accessory relay exhibit this symptom? | Go to Step 5 | Go to Step 4 |
| 4 | Install a scan tool. Select body control module (BCM) data in data display. Close all of the doors. Turn ON the ignition, with the engine OFF. Wait 5 seconds, then turn the ignition OFF. Wait for the RAP time-out. Does the scan tool display the Accessory power mode, then time-out, and display Off-Awake or OFF power mode? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 15 |
| 5 | Turn OFF the ignition. Disconnect the accessory relay. Turn ON the ignition, with the engine OFF. With a test lamp that is connected to a good ground, probe the battery positive voltage circuit of the accessory relay. Does the test lamp illuminate? | Go to Step 6 | Go to Step 12 |
| 6 | Connect a test lamp across the relay coil circuit of the accessory relay. Turn ON the ignition, with the engine OFF. Does the test lamp illuminate? | Go to Step 9 | Go to Step 7 |
| 7 | Test the accessory relay control circuit for a short to ground or an open. Turn the ignition ON, with the engine OFF, when testing for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 8 |
| 8 | Test the accessory relay ground circuit for an open. Did you find and correct the condition? | Go to Step 17 | Go to Step 15 |
| 9 | Turn OFF the ignition. Reconnect the accessory relay. Turn ON the ignition, with the engine OFF. With a test lamp that is connected to a good ground, probe the accessory relay switched output circuit at the accessory relay. Does the test lamp illuminate? | Go to Step 10 | Go to Step 11 |
| 10 | Repair the open in the accessory relay switched output circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the replacement? | Go to Step 17 | |
| 11 | Inspect for poor connections at the accessory relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 14 |
| 12 | Test the accessory relay switched output circuit for a short to ground. Did you find and correct the condition? | Go to Step 17 | Go to Step 13 |
| 13 | Repair the battery positive voltage circuit of the accessory relay. Refer to Wiring Repairs in Wiring Systems. Reconnect the accessory relay. Did you complete the repair? | Go to Step 17 | |
| 14 | Replace the accessory relay. Did you complete the replacement? | Go to Step 17 | |
| 15 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 17 | Go to Step 16 |
| 16 | IMPORTANT: Perform the module setup procedure, if required. Replace the BCM. Refer to Body Control Module Replacement .Did you complete the procedure? | Go to Step 17 | |
| 17 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| IMPORTANT |
|---|
| Perform the module setup procedure, if required. |
Retained Accessory Power (RAP) Inoperative
Control Module References
| Control Module | Schematic | Repair Instruction | Programming and Setup |
|---|---|---|---|
| Diagnostic System Check - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle DTC Symptom Description Symptoms - Vehicle | |||
| Audio Amplifier | Radio/Audio System Schematics | Amplifier Replacement (Coupe and Sedan) or Amplifier Replacement (Convertible) | This device requires no programming or setup |
| Body Control Module | Body Control System Schematics | Body Control Module Replacement | Body Control Module Programming and Setup |
| Communication Interface Module (OnStar®) | OnStar Schematics | Communication Interface Module Replacement | OnStar Reconfiguration after VCIM replacement. |
| Digital Radio Receiver | Radio/Audio System Schematics | Receiver Replacement - Digital Radio (Convertible) or Receiver Replacement - Digital Radio (Coupe) or Receiver Replacement - Digital Radio (Sedan) | Digital Radio Receiver Setup after DRR replacement. |
| Electronic Brake Control Module | ABS Schematics | Electronic Brake Control Module Replacement | Service Programming System (SPS) after EBCM replacement. |
| Engine Control Module (2.4L and 3.9L engines) | Engine Controls Schematics for the 2.4L engine or Engine Controls Schematics for the 3.9L engine | Engine Control Module (ECM) Replacement for the 2.4L engine or Engine Control Module (ECM) Replacement for the 3.9L engine | Engine Control Module Programming and Setup |
| Folding Top Control Module | Folding Top Control Module Replacement | This device requires no programming or setup | |
| Garage Door Opener | Garage Door Opener Replacement | Garage Door Opener Programming - Universal after GDO replacement. | |
| Heated Seat Control Module | Driver Seat Schematics or Passenger Seat Schematics | Heated Seat Control Module Replacement - Front | This device requires no programming or setup |
| HVAC Control Module | HVAC Schematics (with C68) or HVAC Schematics (with C60) | HVAC Control Module Replacement (with C68) or HVAC Control Module Replacement (with C60) | HVAC Control Module Programming and Setup |
| Ignition Control Module | Engine Controls Schematics | Ignition Control Module Replacement | This device requires no programming or setup |
| Inflatable Restraint Passenger Presence System | SIR Schematics | Inflatable Restraint Passenger Presence System Replacement - Front (w/Heated Seat) or Inflatable Restraint Passenger Presence System Replacement - Front (w/o Heated Seat) | Passenger Presence System Programming and Setup |
| Inflatable Restraint Sensing and Diagnostic Module | SIR Schematics | Inflatable Restraint Sensing and Diagnostic Module Replacement | Inflatable Restraint Sensing and Diagnostic Module Programming and Setup |
| Instrument Panel Cluster | Instrument Cluster Schematics | Instrument Panel Cluster (IPC) Replacement | This device requires no programming or setup |
| Powertrain Control Module (3.5L engine) | Engine Controls Schematics | Powertrain Control Module (PCM) Replacement | Powertrain Control Module Programming and Setup |
| Power Steering Control Module | Power Steering System Schematics | Steering Column Replacement (Electronic) or Steering Column Replacement (Hydraulic) | Power Steering Control Module Programming and Setup |
| Radio | Radio/Audio System Schematics | Radio Replacement | Radio Setup after radio replacement. |
| Remote Control Door Lock Receiver | Keyless Entry Schematics | Remote Control Door Lock Receiver Replacement (Coupe) or Remote Control Door Lock Receiver Replacement (Convertible) or Remote Control Door Lock Receiver Replacement (Sedan) | Transmitter Programming after RCDLR replacement. |
| Sunroof Motor/Actuator | Power Sunroof Schematics | Sunroof Motor/Actuator Replacement (C3Y) or Sunroof Motor/Actuator Replacement (CF5) | Sunroof Control Module Programming and Setup (W/RPO CF5) or Sunroof Control Module Programming and Setup (W/RPO C3Y) |
| Theft Deterrent Control Module | Theft Deterrent System Schematics | Theft Deterrent Control Module Replacement | Theft Deterrent Control Module Programming and Setup |
| Transmission Control Module | Automatic Transmission Controls Schematics for the 4T40-E/4T45-E transmission or Automatic Transmission Controls Schematics for the 4T65-E transmission | Automatic Transmission Controls Schematics for the 4T40-E/4T45-E transmission or | Transmission Control Module Programming and Setup |
Control Module References
Data Link References
This table identifies which serial data link that a particular module uses for in-vehicle data transmission. Some modules may use more than one data link to communicate. Some modules may have multiple communication circuits passing through them without actively communicating on that data link. This table is used to assist in correcting a communication malfunction. For the description and operation of these serial data communication circuits, refer to Data Link Communications Description and Operation .
| Control Module | Data Link Type | Diagnostic Procedure |
|---|---|---|
| Schematic Reference: Data Link Connector (DLC) Schematics | ||
| Body Control Module (BCM) | High Speed GMLAN Low Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device and Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Digital Radio Receiver (DRR) | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Electronic Brake Control Module (EBCM) | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| HVAC Control Module | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Instrument Panel Cluster (IPC) | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Inflatable Restraint Sensing and Diagnostic Module (SDM) | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Power Steering Control Module (PSCM) | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Powertrain Control Module (PCM) Manual Transmission Only | High Speed GMLAN | Scan Tool Does Not Communicate with High Speed GMLAN Device |
| Radio | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Remote Playback Device - CD Player (CDX) | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Theft Deterrent Module (TDM) | Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
| Vehicle Communication Interface Module (VCIM) | High Speed GMLAN - pass through only Low Speed GMLAN | Scan Tool Does Not Communicate with Low Speed GMLAN Device |
Data Link References
Body Control Module (BCM) Programming/RPO Configuration
A new body control module (BCM) must be programmed with the proper regular production option (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 various RPO's available for the vehicle. Ensure that the following conditions exist in order to prepare for BCM programming
- This entire procedure has been reviewed before starting
- The battery is fully charged.
- A CANdi module is installed between the vehicle and the scan tool.
- The ignition switch is in the ON position.
- The data link connector (DLC) is accessible.
- All disconnected modules and devices are reconnected before programming.
BCM Programming
| IMPORTANT | Use extreme care when verifying both the VIN and Odometer reading that is set in the service BCM. Once the VIN and Odometer are set in the replacement BCM it is impossible to change them, and if there is a mismatch, the part will be rendered useless. |
To setup a new replacement BCM select Vehicle Control Systems, then navigate to Computer/Integrating Systems, once in the Computer/Integrating Systems menu select Module Replacement/Setup and follow the instructions on the scan tool. After the setup procedure it is necessary to perform the Remote Start setup procedure and BPP Sensor Calibration procedure. Refer to the Important's below for further information.
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.
Theft Deterrent Programming Procedures
| IMPORTANT | If any module or device listed is replaced, programming of the module must be done prior to performing the theft deterrent programming procedure. |
Perform the theft deterrent programming procedure if any of the following components have been replaced
- The body control module (BCM)
- The powertrain control module (PCM) Refer to «Programming Theft Deterrent System Components»(ref-243000-S12754242352006082100000) in Theft Deterrent for the proper procedure.
SDM Part Number Learn Procedure
If the SDM is replaced the SDM part number must be learned by the BCM. Using a scan tool navigate to Vehicle Control Systems, Module Setup, Supplemental Inflatable Restraints then select Setup SDM Part Number In BCM. Follow the on screen directions.
| IMPORTANT | After programming, perform the following to avoid future misdiagnosis |
- Turn the ignition OFF for 10 seconds.
- Connect the scan tool to the data link connector.
- Turn the ignition ON with the engine OFF.
- Use the scan tool in order to retrieve history DTCs from all modules.
- Clear all history DTCs.
Data Link Connector (DLC)
The data link connector (DLC) is a standardized 16-cavity connector. Connector design and location is dictated by an industry wide standard, and is required to provide the following
- Pin 1 GMLAN low speed communications terminal
- Pin 4 Scan tool power ground terminal
- Pin 5 Common signal ground terminal
- Pin 6 High speed GMLAN serial data bus (+) terminal
- Pin 14 High speed GMLAN serial data bus (-) terminal
- Pin 16 Scan tool power, battery positive voltage terminal
Serial Data Reference
The scan tool communicates over the various busses on the vehicle. When a scan tool is installed on a vehicle, the scan tool will try to communicate with every module that could be optioned into the vehicle. If an option is not installed on the vehicle, the scan tool will display No Comm for that options control module. In order to avert misdiagnoses of No Communication with a specific module, refer to Data Link References for a list of modules, the busses they communicate with, and the RPO codes for a specific module.
Power Mode Master
This vehicles body control module (BCM) functions as the power mode master (PMM). Refer to Power Mode Description and Operation for a complete description of power mode functions.
Serial Data Gateway
The body control module (BCM) in this vehicle functions as a translator between the High and Low speed GMLAN busses. The 2 communication protocols use the BCM to translate communicated serial data messages between the control modules over the 2 serial data busses.
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
- A/C compressor request-Refer to «Air Temperature Description and Operation»(ref-242994-S34806165472006082100000) in HVAC Systems - Manual.
- A/C cooling fan-Refer to «Air Delivery Description and Operation»(ref-242994-S11484414692006082100000) in HVAC Systems - Manual.
- Battery rundown protection (inadvertent power) - Refer to «Interior Lighting Systems Description and Operation»(ref-242978-S32727780052006082100000) in Lighting Systems.
- Bulb check-Refer to «Instrument Panel Cluster (IPC) Description and Operation»(ref-242974-S37520336162006082100000) in Instrument Panel, Gages, and Console.
- Chimes-Refer to «Indicator/Warning Message Description and Operation»(ref-242974-S31211547042006082100000) in Instrument Panel, Gages, and Console. Check gages Door ajar warning Headlamps ON Key-in-ignition Oil reset Park brake warning Seat belt not fastened Turn signal ON
- Door lock interface-Refer to «Power Door Locks Description and Operation»(ref-242983-S08294248512006082100000) in Doors.
- Electronic power steering (EPS) - Refer to «Power Steering System Description and Operation (Electronic Power Steering)»(ref-243012-S35248966452006082100000) or «Power Steering System Description and Operation (Hydraulic Power Steering)»(ref-243012-S31456424102006082100000) in Power Steering System.
- Engine coolant level sensing-Refer to «Cooling System Description and Operation»(ref-243023-S15509491822006082100000) in Engine Cooling.
- Exterior and interior lighting control-Refer to «Exterior Lighting Systems Description and Operation»(ref-242978-S18925297112006082100000) in Lighting Systems. Automatic lighting control Daytime running lamps (DRL) Fog lamps Park brake lights Turn hazard lamps
- Gage control-Refer to «Instrument Panel Cluster (IPC) Description and Operation»(ref-242974-S37520336162006082100000) in Instrument Panel, Gages, and Console.
- Horn interface-Refer to «Horns System Description and Operation»(ref-242982-S16126715862006082100000) in Horns.
- Instrument cluster indicator control-Refer to «Instrument Panel Cluster (IPC) Description and Operation»(ref-242974-S37520336162006082100000) in Instrument Panel, Gages, and Console.
- Interior lighting-Refer to «Interior Lighting Systems Description and Operation»(ref-242978-S32727780052006082100000) in Lighting Systems.
- Key-in-ignition sensing-Refer to «Indicator/Warning Message Description and Operation»(ref-242974-S31211547042006082100000) in Instrument Panel, Gages, and Console.
- Parking brake state sensing-Refer to «Brake Warning System Description and Operation»(ref-243022-S38354034302006082100000) in Hydraulic Brakes.
- Retained accessory power (RAP) - Refer to «Retained Accessory Power (RAP) Description and Operation»(ref-242975-S09868106482006082100000) .
- Rear compartment interface-Refer to «Power Door Locks Description and Operation»(ref-242983-S08294248512006082100000) in Doors.
- Rear defogger-Refer to «Rear Window Defogger Description and Operation»(ref-242981-S36401569202006082100000) in Stationary Windows.
- Remote function control-Refer to «Keyless Entry System Description and Operation»(ref-242998-S34367301462006082100000) in Keyless Entry.
- Seat belt use sensing-Refer to «Seat Belt System Description and Operation»(ref-243027-S17544342422006082100000) in Seat Belts.
- Content theft deterrent-Refer to «Theft Systems Description and Operation»(ref-243000-S35750405072006082100000) in Theft Deterrent.
- Vehicle theft deterrent-Refer to «Vehicle Theft Deterrent (VTD) Description and Operation»(ref-243000-S26105651472006082100000) in Theft Deterrent.
- Washer solvent level sensing-Refer to «Wiper/Washer System Description and Operation»(ref-243004-S11950396082006082100000) in Wipers/Washer Systems.
- Wiper/washer-Refer to «Wiper/Washer System Description and Operation»(ref-243004-S11950396082006082100000) in Wipers/Washer Systems.
Serial Data Power Mode Master
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 3-wire Ignition Switch table below illustrates the state of these inputs in correspondence to the ignition switch position
| Ignition Switch Position | Accessory | Ignition 1 | Off/Run/Crank | Power Mode Transmitted |
|---|---|---|---|---|
| IMPORTANT: States marked with the * indicate a derived positive voltage level of 3 volts. States marked with the ** indicate a derived positive voltage level of 4 volts. | ||||
| Off | 0 | 0 | 0 Key out 1 Key in | OFF/Awake or RAP |
| Start | 0 | 1 | 1 * | Crank |
| Accessory | 1 | 0 | 0 | Accessory |
| Run | 1 | 1 | 1 ** | Run |
| IMPORTANT |
|---|
| States marked with the * indicate a derived positive voltage level of 3 volts. States marked with the ** indicate a derived positive voltage level of 4 volts. |
3-Wire Ignition Switch
Relay Controlled Power Mode
The body control module (BCM) uses the discrete ignition switch inputs Off/Run/Crank, Accessory, and ignition 1, to distinguish the correct power mode. The ignition 1 circuit is also routed to the Run/Crank relay for relay controlled power feeds during the appropriate power mode. The BCM, after determining the desired power mode, will activate the appropriate relays for that power mode.
Run/Crank Relay
The run/crank relay control circuit is connected to a constant ground and is switched by the ignition 1 circuit or the BCM. The BCM, will in lieu of the ignition switch position, activate the Run/Crank relay during a remote start event. The Run/Crank relay supplies a power signal to the following circuits, when the a Run or Crank power mode is selected
- Automatic transmission shift indicator
- Automatic transmission (A/T)
- Switched power feeds to the BCM
- Electronic brake control module (EBCM)
- Electronic ignition module (spark control)
- Electronic power steering module (EPS)
- Fuel injectors
- Powertrain control module (PCM)
- Park neutral position (PNP) switch
Accessory (ACC) Relay
The adaptive cruise control (ACC) 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 ACC relay is also energized by the BCM to supply power during the retained accessory power (RAP) mode. The following devices are controlled by this relay
- Inside rearview mirror
- Heated seats
- Power windows
- Sunroof
- Wiper washers switch
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.
The BCM will enter a wake-up state, if any of the following wake-up inputs are detected
- Activity on the serial data line
- Detection of a battery disconnect and reconnect condition
- Headlamps are ON.
- Ignition is turned ON.
- Key-in-ignition switch
- Park lamps are ON.
- RFA message
The BCM will enter a sleep state when all of the following conditions exist
- The ignition switch is OFF.
- No activity exists on the serial data line.
- No outputs are commanded.
- No delay timers are actively counting.
- 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 or OFF-ASLEEP message to the other systems on the serial data line.
Serial Data Control of Retained Accessory Power (RAP)
The modules receive the power mode message from the body control module (BCM) over the serial data circuits, indicating when the retained accessory power (RAP) power mode is current. The BCM monitors the ignition switch position, battery condition and passenger compartment doors status to determine whether RAP should be initiated. The modules then support the operation of the systems under their control as required by their RAP power mode operation.
RAP will end when one of the following conditions is met
- The BCM receives an input indicating the opening of any compartment door.
- The BCM internal timer for the RAP expires after approximately 10 minutes.
- The BCM detects a decrease in battery capacity below a prescribed limit.
- The Radio uses an exclusive RAP message that can not be circumvented by any door but the drives door.
The BCM then sends a serial data power mode message ending the RAP function.
The radio is the only module that is controlled by the serial data circuits.
Relay Control of Retained Accessory Power (RAP)
The body control module (BCM) keeps the accessory relay energized during all power modes, except Off-Awake and Crank.
The devices powered by the accessory relay during the retained accessory power (RAP) power mode are the sunroof and windows.