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DTC U0101: Lost Communication with TCM [12/2015 - 08/2016]: Description

WARNING: This page is about a different car, the 2016 Toyota Sienna. However, it is still accessible from the selected car via links, so may be relevant.

The Transmission Control Module (TCM) and ECM perform 2-way communication with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine speed, required engine torque, warning indicators in the combination meter assembly, DTCs and other data. The ECM sends signals to the TCM concerning engine speed, opening angle of the throttle valve, temperature of intake air, temperature of engine coolant, engine torque and other data. If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and store a DTC.

DTC No. DTC Detection Condition Trouble Area
U0101
  1. Following conditions are met for 1.25 seconds
  2. (1 trip detection logic):
    1. Ignition switch ON
    2. Battery voltage 10.5 V or higher
    3. No intercommunication between ECM and TCM
  • ECM to TCM circuit
  • TCM
  • ECM