U2104

DTC U2104

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. When no communication on the CAN serial data line is detected, DTC U2104 will result.

CONDITIONS FOR RUNNING THE DTC
The CAN circuits are monitored continuously by the modules on the circuit. The only requirement is that the modules are in a RUN power mode.

CONDITIONS FOR SETTING THE DTC
The module setting the DTC has attempted to establish communications on the CAN circuits more than 7 times.

ACTION TAKEN WHEN THE DTC SETS
- The DTC is set as both current and history, the modules on the CAN network each take separate actions as listed:
- ECM and BCM:
- Turn ON the malfunction indicator lamp (MIL) during the second consecutive drive cycle with the error detected.
- Record the operating conditions at the time of turning ON the MIL and store the data as Freeze Frame information.

CONDITIONS FOR CLEARING THE MIL/DTC
- A current DTC clears and the MIL is turned OFF when the fault is no longer detected after the 3rd consecutive drive cycle.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the fault, or does not reoccur after 40 consecutive drive cycles.
- A history DTC clears if there is a battery disconnect.

TEST

Steps 1-6: