U0101

DTC UO101 Lost Communication with TCM

Circuit Description

The ECM and the transmission control module (TCM) communicate control and diagnostic information via a controller area network (CAN) communication bus. The ECM monitors CAN operational status by expecting a constant flow of messages from the TCM. If the ECM fails to receive an expected message from the TCM this DTC will set.

Condition for Running the DTC

^ DTC U0073 is not set.
^ The battery voltage is between 8to 16 volts.
^ The ignition switch is ON.

Condition for Setting the DTC

^ The ECM detects that the CAN Bus messages from the TCM are not being received.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

^ If an intermittent condition is suspected refer to Intermittent Conditions in this section.
^ Parallel resistance of the 120 resistor in the ECM and the TCM should be 60.

Notice: If the TCM has DTCs set, clear the DTCs in the TCM first.

Circuit/System Testing DTC UO1O1