U2103

DTC U2103

CIRCUIT DESCRIPTION
The controller area network (CAN) serial data line is a high speed serial data bus used to communicate information between the engine control module (ECM), body control module (BCM), and the transmission control module (TCM). Typical data-transmission speeds must be high enough to ensure that the required real-time response is maintained. The CAN serial data line does not communicate with the scan tool via the data link connector (DLC). CAN serial data information is interpreted by the BCM and transmitted to the serial data line by the BCM. The CAN bus is continuously monitored by the modules on the serial data bus.

CONDITIONS FOR RUNNING THE DTC
- Supply voltage to the modules that are in the normal operating range.
- The ignition is cycled from OFF to RUN.

CONDITIONS FOR SETTING THE DTC
Each controller on the CAN serial data circuit monitors the activity or traffic on the bus. The module setting the DTC does not receive CAN formatted messages from all of the modules it expected to. This indicates that there may be more or fewer controllers actively communicating on the bus than programmed. After the seventh attempt, the module sets DTC U2102- More Controllers or DTC U2103- Fewer Controllers.

ACTION TAKEN WHEN THE DTC SETS
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The malfunction indicator lamp (MIL) turns ON during the second consecutive drive cycles with the error detected in the ECM.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
- The ECM records the operating conditions at the time of turning ON the MIL and stores the data as Freeze Frame information.

CONDITIONS FOR CLEARING THE DTC
- A current DTC Last Test Failed clears when the diagnostic runs and passes after 3 consecutive drive cycles.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- Clear the DTC with a scan tool.
- The MIL turns OFF.

TEST

Steps 1-5: