Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Lost Communication with ECM / PCM "A" (U0100,U0126,U0129)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Drivetrain / Mf1a (transfer / 4wd / Awd) / Dynamic Torque Control Awd System / Lost Communication with ECM / PCM "A" (U0100,U0126,U0129)

DESCRIPTION

The 4WD ECU assembly receives signals from the ECM, skid control ECU (brake actuator assembly) and steering sensor via CAN communication.

When DTCs indicating a CAN communication system malfunction are output, repair the CAN communication system before repairing each corresponding sensor.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

U0100

Lost Communication with ECM / PCM "A"
  • When both of the following continue for 2 seconds or more:
    • The IG1 terminal voltage is 10 V or more.
    • At a vehicle speed of 60 km/h (38 mph) or more, communication with the ECM cannot be performed.
  • CAN communication system
  • 4WD ECU assembly
  • ECM

U0126

Lost Communication with Steering Angle Sensor Module
  • When both of the following continue for 1 second or more:
    • The IG1 terminal voltage is 10 V or more.
    • Communication with the steering sensor cannot be performed.
  • When all of the following occur 10 times consecutively:
    • The IG1 terminal voltage is 10 V or more.
    • A communication malfunction with the steering sensor occurs once within 5 seconds, 10 times or more within 60 seconds.
  • CAN communication system
  • 4WD ECU assembly
  • Steering sensor

U0129

Lost Communication with Brake System Control Module
  • When the following continues for 3 seconds or more:
    • The IG1 terminal voltage is 10 V or more.
    • Communication with the skid control ECU (brake actuator assembly) cannot be performed.
  • CAN communication system
  • 4WD ECU assembly
  • Skid control ECU (Brake actuator assembly)

PROCEDURE

1.

CHECK FOR DTC

(a) Check for DTCs.

Click here

Chassis > Four Wheel Drive > Trouble Codes

(b) Write down any output DTCs.

NEXT

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

    Control Module Communication Bus Off (U0073)
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