Action Taken When the DTCs Sets
- The module suspends all message transmission.
- The module uses default values for all parameters received on the GMLAN serial data circuits.
- The module inhibits the setting of all other GMLAN communication DTCs.
- The module suspends all message transmission.
- The module uses default values for all parameters received on the high speed GMLAN serial data circuits.
- The module inhibits the setting of all other high speed GMLAN 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 | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Turn the ignition switch to the LOCK position. Disconnect the RAP relay. Open the driver door. Inspect the power windows and radio for correct operation. Do the radio and the power windows operate? | Go to Step 3 | Go to Step 4 |
| 3 | Repair the short to battery in the power windows and radio feed circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | |
| 4 | Using a test lamp connected to a good ground, probe the RAP relay control circuit. Does the test lamp illuminate? | Go to Step 6 | Go to Step 5 |
| 5 | Replace the RAP relay. Did you complete the replacement? | Go to Step 7 | |
| 6 | Replace the body control module. Refer to Did you complete the replacement? | Go to Step 7 | |
| 7 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Retained Accessory Power (RAP) On After Timeout
Retained Accessory Power (RAP) Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Retained Accessory Power (RAP) Schematics | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Close the driver and passenger doors. Turn ON the ignition, with the engine OFF. Turn OFF the ignition. Do the retained accessory power functions (power windows, radio) operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Disconnect the RAP relay. Connect a test lamp between the RAP relay control circuit and the RAP relay ground circuit. Close the driver and passenger doors. Turn ON the ignition, with the engine OFF. Turn OFF the ignition. Does the test lamp illuminate? | Go to Step 5 | Go to Step 4 |
| 4 | Test the RAP relay control circuit and ground circuit for opens. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 7 |
| 5 | Connect a test lamp between the RAP relay supply voltage circuit and the RAP relay ground circuit. Does the test lamp illuminate? | Go to Step 8 | Go to Step 6 |
| 6 | Repair the open in the RAP relay supply voltage circuit. Did you complete the repair? | Go to Step 11 | |
| 7 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. | Go to Step 11 | Go to Step 10 |
| 8 | Test the RAP relay output circuit for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 9 | Replace the RAP relay. Did you complete the replacement? | Go to Step 11 | |
| 10 | Replace the BCM. Did you complete the replacement? | Go to Step 11 | |
| 11 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Retained Accessory Power (RAP) Inoperative
Control Module References
| Control Module | Repair/Reprogramming Instructions | Diagnostic System Check | Schematic |
|---|---|---|---|
| Body Control Module (BCM) | Body Control Module Replacement Body Control Module (BCM) Programming/RPO Configuration | Diagnostic System Check - Vehicle | Body Control System Schematics |
| Electronic Brake Control Module (EBCM) | Electronic Brake Control Module Replacement | Diagnostic System Check - Vehicle | ABS Schematics |
| Instrument Panel Cluster (IPC) | Instrument Panel Cluster (IPC) Replacement Instrument Panel Cluster (IPC) Programming/Synchronization | Diagnostic System Check - Vehicle | Instrument Cluster Schematics |
| Engine Control Module (ECM) | Engine Control Module (ECM) Replacement Engine Control Module Programming and Setup | Diagnostic System Check - Vehicle | Engine Controls Schematics |
| Inflatable Restraint Sensing and Diagnostic Module (SDM) | Inflatable Restraint Sensing and Diagnostic Module Replacement | Diagnostic System Check - Vehicle | SIR Schematics |
| Radio | Radio Replacement | Diagnostic System Check - Vehicle | Radio/Audio System Schematics Steering Wheel Controls Schematics |
| Transmission Control Module | Transmission Control Module (TCM) Replacement | Diagnostic System Check - Vehicle | Automatic Transmission Controls Schematics |
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 |
|---|---|
| Engine Control Module (ECM) | GM LAN |
| Powertrain Interface Module (PIM) | GM LAN UART Serial Data |
| Instrument Cluster Panel (IPC) | UART Serial Data |
| Body Control Module (BCM) | UART Serial Data |
| Inflatable Restraint Sensing and Diagnostic Module (SDM) | UART Serial Data |
| Electronic Brake Control Module (EBCM) | GM LAN |
| Radio | UART Serial Data |
| Transmission Control Module (TCM) | GM LAN |
Data Link References
ECM/PIM/BCM Security Link
If the engine control module (ECM), powertrain interface module (PIM) and/or the body control module (BCM) are replaced, the new modules must be security linked to each other. If the procedure is not performed, the engine will not crank or run. If the BCM has been replaced then replace and program all of the key fob transmitters for each of the vehicle's keys. The replacement BCM comes with a new security number replacing the number on the vehicle's security card.
Linking the BCM to the PIM
With the Tech 2, perform the following procedures
- Replace the key fob transmitter for each of the vehicle's keys.
- Connect the Tech 2 to the data link connector (DLC) and select: Diagnostic/Pontiac GTO/Body/Body Control Module/Special Functions/Program Key Fobs, and follow the screen instructions to program the key fob transmitters. Refer to «Transmitter Programming»(ref-201053-S24767596122005102400000) Transmitter Programming for further information.
- When prompted, enter the security code located on the new BCM and follow the Tech 2 instructions. If a valid code is entered, the new BCM and key fobs will now be linked to each other. The key fobs will be write protected by the BCM and can never be link to another BCM.
- After successfully programming the new key fobs, backup to Special Functions and select Link BCM to PIM and enter the new BCM security number. This will link the new BCM to the PIM and the security information in the PIM will change. Therefore, the PIM and the ECM will have to be linked. Perform a Vehicle Theft Deterrent relearn through SPS Programming. This will link the PIM to the ECM.
Linking the PIM to the BCM
| IMPORTANT | If a new Powertrain Interface Module has been installed in the Vehicle, it must be security linked to the Body Control Module and the Engine Control Module. It is recommended that you link the PIM to the BCM before linking to the ECM. For information on linking the PIM to the ECM refer to Engine Control Module Programming and Setup . |
Connect the Tech 2 to the data link connector (DLC) and select: Diagnostic/Pontiac GTO/Body/Powertrain Interface Module/Special Functions/Link BCM to PIM, and follow the screen instructions.
PIM Configuration
This procedure will configure the PIM for either an automatic or manual transmission.
- Connect the Tech 2 to the data link connector (DLC) and select: Diagnostic/Pontiac GTO/Body/Powertrain Interface Module/Special Functions/PIM Configuration, and follow the screen instructions.
- Select the transmission type and press the soft key.
Linking the BCM to the PIM without Tech 2
Without the Tech 2, perform the following procedure
- Replace the key fob transmitter for each of the vehicle's keys. Program the key fob transmitter. Refer to «Transmitter Programming»(ref-201053-S24767596122005102400000) Transmitter Programming in Keyless Entry.
- Turn ignition ON with a valid key.
- Leave the ignition in the ON position for 10 minutes. After 10 minutes the car horn will chirp once.
- Turn the ignition OFF within 5 minutes after the horn chirp and ON again within 5 seconds. If the timing expires for this step, the sequence will be cancelled.
- Leave the key in the ON position for 10 minutes. After 10 minutes the car horn will chirp twice.
- Turn the ignition OFF within 5 minutes after the horn chirps and ON again within 5 seconds.
- Leave the key in the ON position for 10 minutes, after 10 minutes the car horn will chirp three times. During the three horn chirps the BCM and PIM are being linked.
- Turn the ignition OFF, and wait 5 seconds.
- Turn the ignition ON and leave the ignition in the ON position for 10 minutes.
- Turn the ignition OFF, and wait 5 seconds.
- Turn the ignition ON and leave the ignition in the ON position for 10 minutes.
- Turn the ignition OFF, and wait 5 seconds.
- Turn the ignition ON and leave the ignition in the ON position for 10 minutes.
- The ECM is now ready to relearn the password from the PIM on the next ignition switch transition from OFF to CRANK.
- Turn the ignition ON. Linking is now completed.
- Turn the ignition to crank and run engine at idle speed, to confirm the linking procedure has been successful.
Body Control Module
The body control module (BCM) controls various vehicle electrical systems or features from one central module, instead of using individual modules for each system or feature.
The BCM is located beneath the instrument panel cluster (IPC) to the right of the steering column and is mounted in a flat, horizontal position. The BCM fitted to various levels of vehicles is physically the same, but with different functions in the BCM software.
| IMPORTANT | Disconnect and remove all vehicle modules, after disconnecting the battery, before performing any welding anywhere on the vehicle. Failing to do this can cause permanent damage to the modules. |
If the BCM is to be replaced, ensure that the correct BCM is used. The last 3 digits of the BCM part number identify the BCM.
BCM Features
- Central door locking with auto lock in drive
- Rear compartment release with speed interlock
- Power window system with driver and passenger express down
- Approach illumination at night
- Dome lamp delay control entry delay, central locking, and ignition off courtesy illumination
- Intermittent wiper control with road speed dependent variable dwell
- Instrument dimming control
- Automatic lights off with adjustable delay
- Automatic lights on with twilight sentinel
- Theft deterrent system vehicle immobilization and entry alarm
- Battery saver Reduce standing current Courtesy and compartment illumination Timed cut-out Pre-delivery 3 minute cut-out
- Remote control via coded key Remote central locking with two-stage unlock Remote rear compartment release
- Air bag deployment vehicle shutdown
- Heated rear window
- Air conditioning interface system (A/C switch)
- Accessory power control (delay accessories bus)
- Serial data interface
Communication
The engine control module (ECM) uses GMLAN communication, while all other control modules, including the body control module (BCM), communicate serial data in universal asynchronous receiver and transmitter (UART). The GMLAN communication is more sophisticated than UART and as such, requires a powertrain interface module (PIM) to convert GMLAN into UART. In simple terms, the ECM communicates in a different language than the other control modules and therefore requires the PIM to translate information into the same language as the other control modules.
The PIM is mounted behind the passenger-side shroud lower trim assembly. Specific software has been developed for use with the scan tool to assist with fault-finding vehicle electrical systems, including the various BCM functions and controls. Scan tool connection for BCM serial data communication is via the data link connector (DLC), attached to the lower right-hand trim of the instrument panel (I/P), to the right of the steering column.
Serial Communication
The vehicle system control modules, as well as the TECH 2 diagnostic scan tool, communicate with each other via the serial communication lines using serial data. Serial data transfers information, one bit at a time, over a single line called the data bus. Except for the engine control module (ECM), all control modules communicating on the data bus use universal asynchronous receiver and transmitter (UART) communication. The UART is a 5-volt data line that toggles the voltage to ground (0 volt) at a fixed bit pulse width during communication. The UART transmits data at the rate of 8.2 kilobits per second (8192 bits per second). In UART communications, when there is no communication on the data line, the system voltage is 5 volts.
Body Control Module Battery Saver Mode
The body control module (BCM) battery saver mode provides vehicle battery protection through reduced current consumption. After a preset delay period of 15 minutes has elapsed, as controlled by the shut down timer, the BCM
- De-energizes the interior illumination relay, which supplies battery voltage to all interior dome, ignition lock, glove compartment, and rear compartment lamps-This protects the battery when a lamp is mistakenly left on because a door is left open, or a faulty illumination circuit or component is causing excess current consumption.
- De-energizes the power window relay-This action is separate from the normal power window off delay function.
- Disables the BCM inputs normally not required when the ignition is OFF-This reduces the BCM current consumption.
If the BCM is in battery saver mode, all the BCM inputs are re-enabled when
- The bonnet, rear compartment or any door is opened.
- The BCM receives a valid RF key lock, unlock, or rear compartment signal.
- The ignition switch is turned ON or to the accessories position.
- The doors are unlocked via the driver door microswitch.
- TECH 2 is communicating with the BCM.
- The headlamp switch is cycled from OFF to ON or from ON to OFF.
- The rear compartment release switch, located in the glove box, is operated.
- The alarm is activated.
- The hazard switch is activated.
Pre-Delivery Mode
To provide additional battery protection, the vehicle is delivered with the body control module (BCM) in pre-delivery mode. In this mode the battery saver period is set to 3 minutes. Pre-delivery mode is disabled once the vehicle has travelled for a total of 30 minutes at speeds above 20 km/h (12 mph). This value is estimated to be the equivalent period prior to customer delivery. Pre-delivery mode may be enabled or disabled by using the trip computer buttons and multifunction display (MFD). Pre-delivery mode may also be enabled and disabled using a scan tool.