Toyota Tundra Service Manual: 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

Trouble Area

U0100

CAN communication system

U0122

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

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

USE SIMULATION METHOD TO CHECK

Toyota Tundra Service Manual > Touch Select 2-4 And High-low System: Four Wheel Drive (4WD) Range Signal Circuit Range / Performance (P279E)
DESCRIPTION This DTC is detected if the transfer position switch 2-4 terminal and LO terminal signals are simultaneously received. DTC Code DTC Detection Condition Diagnosis Condition Malfunction Status Malfunction Time Other Trouble Area P279E Ignition switch is ON and engine is running 2-4 termina ...

Toyota Tundra Owners Manual