DTC U2105: CAN BUS PCM ERROR Chevrolet Silverado 2500

Note. For circuit identification, see CONNECTOR IDENTIFICATION and WIRING DIAGRAMS .

Circuit Description

The Transmission Control Module (TCM) can be calibrated to communicate with an electronically-controlled engine via a BUS circuit (SAE J1939). Diagnostic information is also communicated via the BUS circuit. This DTC applies to the 6.6L engine only.

This is a type "B" DTC.

Conditions For Running The DTC

DTC will run under the following conditions

1. The components are powered, and ignition voltage is greater than 9 volts and less than 18 volts.
2. Engine speed is greater than 200 RPM and less than 7500 RPM for 5 seconds.

Conditions For Setting The DTC

DTC will set under one of the following conditions

1. The TCM is calibrated for BUS circuit communication and the TCM detects an error on the Controller Area Network (CAN) link (no engine throttle or torque messages) for 3 seconds.
2. An open at the CAN backbone.

Action Taken When The DTC Sets

TCM performs the following actions if DTC is set

1. DTC is stored in the TCM history.
2. The MIL illuminates on the second occurrence.
3. The TCM uses the default throttle value.
4. The TCM halts shift adapts.
5. The TCM inhibits TCC engagement.

Conditions For Clearing The DTC

DTC will clear under the following conditions

1. A scan tool can clear the DTC from the TCM history.
2. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

Test Description

The numbers listed below refer to step numbers in the diagnostic procedure

1. 2 This step checks for loose CAN connectors.
2. 4 This step checks resistance between terminals No. 29 and 32 on the C1 connector.