Toyota Tundra Service Manual: Lost Communication with ECM / PCM "A" (U0100,U0122)

Toyota Tundra Service Manual / Engine, Hybrid System / Wf1am Transfer / Touch Select 2-4 And High-low System / Lost Communication with ECM / PCM "A" (U0100,U0122)

DESCRIPTION

This DTC is detected if communication is lost between the ECM and skid control ECU.

DTC Code

DTC Detection Condition

  1. Diagnosis Condition
  2. Malfunction Status
  3. Malfunction Time
  4. Other

Trouble Area

U0100
  1. Ignition switch ON
  2. Communication is lost between ECM and 4 wheel drive control ECU
  3. 5 seconds or more
  4. 1 trip detection logic

CAN communication system

U0122
  1. Ignition switch ON
  2. Communication is lost between skid control ECU and 4 wheel drive control ECU
  3. 0.7 seconds or more
  4. 1 trip detection logic

CAN communication system

CAUTION / NOTICE / HINT

NOTICE:

  • When the data in the ECM or skid control ECU is being overwritten, the indicator light may rapidly blink due to the 4 wheel drive control ECU detecting a communication malfunction (blinks at 0.25 second intervals (0.25 seconds on and 0.25 seconds off)), but this is not a malfunction.
  • Clear all DTCs, since DTCs are stored after the data in the ECM or skid control ECU is overwritten.

PROCEDURE

1.

RECONFIRM DTC

(a) Clear the DTCs (See page ).

(b) Check if the same DTCs are output (See page ).

Result

Result

Proceed to

DTC is output

A

DTC is not output

B
A

GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING)

B

USE SIMULATION METHOD TO CHECK

    Terminals Of Ecu

    Invalid Data Received from Vehicle Dynamics Control Module (U0416)

    See More:

    Toyota Tundra Service Manual > Automatic Transmission System: Precaution
    PRECAUTION NOTICE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected (See page ). Perform Reset Memory procedures (A/T initialization) after replacing the automatic transmission assembly, valve body assembly or any of the shift solenoid valves (See page ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2025 Copyright www.ttundra.com
    0.0325