DTC U2108: Lost Communication With Abs Control System (EBTCM): Description

Serial data on the CAN bus is transferred at a rate of 125 kilobytes-1 megabytes per second to ensure "real-time" response is maintained between Engine Control Module (ECM), Electronic Brake/Traction Control Module (EBTCM), and Transmission Control Module (TCM). When ignition switch is turned to ON position, modules begin to transmit data between each other. Each message sent on this data line has a unique identifier to classify the content and a priority assignment to denote importance. With this embedded information, only those modules on the CAN bus that have access to the message can receive the message. When more than one module on the network trys to transmit simultaneously, the message with highest priority gets access first.

The CAN bus circuit is continuously monitored by each module once ignition switch is turned to ON position. The ECM and TCM monitor received messages from EBTCM for corruption or missing messages. DTC U2108 will be set if ECM and/or TCM does not receive a message back from EBTCM 3 seconds after initialization, or if the message is corrupted. If ECM sets DTC U2108, SERVICE ENGINE SOON light will be illuminated on the second consecutive drive cycle that the diagnostics run and fail. If TCM sets DTC U2108, only a malfunction DTC is stored.

A current DTC U2108 in ECM will clear when conditions for setting DTC are no longer present and ECM will turn off CHECK ENGINE SOON light after 3 consecutive drive cycles, ECM battery voltage is interrupted, or a scan tool is used to clear DTCs. A history DTC U2108 in ECM will clear after 40 consecutive warm-up cycles, if no failures are present by this diagnostic or any other emission-related diagnostic.

A current DTC U2108 in EBTCM will clear when conditions for setting DTC are no longer present, or a scan tool is used to clear DTCs. A history DTC U2108 in TCM will clear after 40 consecutive warm-up cycles with no malfunction detected.