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DTC U0101 Lost Communication with TCM: Description

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.

The ECM (engine control unit) intercommunicates with the TCM (transmission control ECU) through the Controller Area Network (CAN)

If there is a problem in this intercommunication, the ECM sets a DTC

DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
U0101 Following conditions are met for 1 25 seconds (1 trip detection logic)
  1. Engine switch on (IG)
  2. Battery voltage is 10 5 V or more
  3. No intercommunication between ECM and TCM
  • ECM
  • TCM
  • ECM to TCM circuit