OBDII Code List

U0101 CADILLAC - Lost Communication With Transmission Control Module

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Faulty Transmission Control Module (TCM)
  • TCM harness is open or shorted
  • TCM circuit poor electrical connection
  • Tech notes

    There is a factory service bulletin for the following Cadillac models:

    2007-2010 Cadillac Escalade Models
    2007-2010 Cadillac XLR
    2009-2010 Cadillac Escalade Hybrid

    Cadillac Factory Service Bulletin OBDII Code U0101

    Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • U0101 Cadillac Description

    Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module.
    OBDII Code U0101 Cadillac - Lost Communication With Transmission Control Module  -

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