U2108

DTC U2108









Circuit Description with 4L30-E Automatic Transmission
The Engine Control Module (ECM) functions as the central module for the Controller Area Network (CAN) bus. The CAN consists of two separate conductors between the ECM and the Transmission Control Module (TCM). Two additional conductors connect the ECM and the Electronic Brake/Traction Control Module (EBTCM). Each module sends information by toggling the circuits high or low to produce pulse-width signals, which the other modules decode.
The CAN data stream contains information such as status messages for relevant operating parameters, device requests and acknowledgments, and state-of-health messages.
When the TCM has not received EBTCM data for a specified amount of time, then DTC U2108 will set. DTC U2108 is a type C DTC.

Condition for Running the DTC
The ignition is ON.

Condition for Setting the DTC
The TCM has not received EBTCM messaging for 1 second.

Action Taken When the DTC Sets
^ The TCM does not request the ECM to illuminate the MIL.
^ The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM records this information as Failure Records.
^ The TCM stores DTC U2108 in TCM history.

Conditions for Clearing the DTC
^ A scan tool can clear the DTC.
^ The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Test Description
The number below refers to the step number on the diagnostic table.
2. Performing this step verifies that an operational abnormality did not take place during TCM power-up, such as Electromagnetic Interference (EMI).