Europe and N. American Emissions

DTC U2105 (European and North American Emissions)

Circuit Description

Modules that are connected to the shared communication circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among 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 usually supervised and some periodic messages are used by the receiver module as an availability indication of the transmitter module.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC U2105 CAN BUS Error

Conditions for Running the DTC

The ignition is ON or the engine is running.

Conditions for Setting the DTC

The transmission control module (TCM) detects that there is no signal on the CAN serial data high or serial data low circuit for more than 0.2 seconds.

Action Taken When the DTC Sets

* The TCM will store the DTC when a failure is detected on the first ignition cycle.
* If communication between the TCM and the ECM resumes anytime after the storing of DTC P2105, a DTC P0700 will set in the ECM and illuminate of the malfunction indicator lamp (MIL).
* The TCM can no longer determine the validity of any information it may or may not receive from the ECM. Therefore the TCM substitutes default values for engine speed, throttle position, and other engine data signals.
* Transmission operation will be reduced, affecting shift points, torque converter clutch operation, and other driveability concerns.

Conditions for Clearing the DTC

* The TCM suspends the request for DTC P0700, when no further failures are detected on the next three ignition cycles.
* The scan tool can clear the DTC from the TCM history.

Diagnostic Aids

* The TCM scan tool data parameters that are received from the ECM, will indicate zero when the CAN serial data circuit failure is active.
* An intermittent malfunction may be caused by a fault in the electrical circuit. Inspect the wiring harness and the components for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).
* Repair any electrical circuit faults that were found. Refer to Wiring Repairs (Component Tests and General Diagnostics).
* The information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.