DTC U2107 V6
DTC Description
This diagnostic procedure supports DTC U2107 -- Lost Communication with Body Control Module (BCM).
Circuit Description
The body control module (BCM) is the vehicle's bus master. The BCM relies on UART protocol to communicate and due to the TCM being on ah GMLAN protocol data bus, the powertrain interface module (PIM) is required to translate the information between each module, in both directions.
Operating information and commands are exchanged between the modules. The modules have pre-recorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervisor time-out period is 250 ms. Each message contains the identification number of the transmitter module.
Refer to Automatic Transmission Controls Schematics , Automatic Transmission Inline 20-Way Connector End View, Automatic Transmission Internal Connector End Views , Automatic Transmission Control Module Connector End Views , and Automatic Transmission Related Connector End Views to aid in diagnosis.
Conditions for Running the DTC
| • | No DTCs U1304, U2100 or U2105. |
| • | Voltage supplied to the BCM is in the normal operating voltage range. |
| • | The vehicle power mode requires serial data communication to occur. |
| • | The DTC U2100 does not have a current status. |
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTC Sets
The module uses a default valve for the missing parameter.
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Diagnostic Aids
| • | A poor connection at the BCM may cause this code to set. |
| • | An improperly powered module may cause this code to set. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2 Checks if Tech 2 can communicate with the BCM. If Tech 2 cannot communicate with BCM, the fault is isolated to the BCM and its circuitry.
3 Checks if Tech 2 can communicate with the PIM. If Tech 2 cannot communicate with the PIM, the fault is isolated to the PIM and it circuitry.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check? Important: Most communication DTCs are set by the powertrain interface module (PIM). Ensure the PIM has not set any DTCs. | Go to Step 2 | |
2 |
Important: Before clearing the DTC, use the Tech 2 Freeze Frame/Failure Record in order to record to transmission parameters at the time the DTC set. Using Tech 2 to clear the DTC(s) erases the Freeze Frame/Failure Record records from the TCM. Transmission / Automatic Transmission / Diagnostic Trouble Codes / Freeze Frame. Diagnostic Trouble Codes / Clear Engine and Transmission DTCs. Body / Body Control Module Are the BCM specifications displayed on Tech 2? | Go to Step 2 | Refer to Body Control Module (BCM) Programming/RPO Configuration |
3 | On Tech 2 select: Body / Powertrain Interface Module. Are the PIM specifications displayed on Tech 2? | Go to Step 3 | Refer to Powertrain Interface Module Description and Operation |
4 | Perform the following procedure in order to verify the repair:
Diagnostic Trouble Codes / Clear Engine and Transmission DTCs Diagnostic Trouble Codes / Read DTC Information. Has DTC U2107 set? | Go to Step 2 | Go to Step 5 |
5 | On Tech 2 select: Diagnostic Trouble Codes / Read DTC information Does Tech 2 display any DTCs you have not diagnosed? | Refer to Scan Tool Data List | System OK |
When all diagnosis and repairs are completed, check the system for correct operation. | |||
