U0121 - Lost Communication With Electronic Brake Control Module

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

  • Faulty Electronic Brake Control Module (EBCM)
  • EBCM harness is open or shorted
  • EBCM circuit poor electrical connection

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

U0121 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 U0121 - Lost Communication With Electronic Brake Control Module - AutoCodes.com

U0121 Information for specific makes

  • U0121 BUICK Lost Communication With Electronic Brake Control Module
  • U0121 CADILLAC Lost Communication With Electronic Brake Control Module
  • U0121 CHEVROLET Lost Communication With Electronic Brake Control Module
  • U0121 DODGE Lost Communication With ABS
  • U0121 FORD Lost Communication With The Anti-lock Brake System Control Module
  • U0121 GMC Lost Communication With Electronic Brake Control Module
  • U0121 HONDA FCAN Malfunction (TCS-PCM)
  • U0121 HUMMER Lost Communication With Electronic Brake Control Module
  • U0121 LINCOLN Lost Communication With The Anti-lock Brake System Control Module
  • U0121 MERCURY Lost Communication With The Anti-lock Brake System Control Module
  • U0121 PONTIAC Lost Communication With Electronic Brake Control Module
  • U0121 SATURN Lost Communication With Electronic Brake Control Module

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U0121 Comments

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