STOP AND START SYSTEM, Diagnostic DTC:U0100, U0121, U0126, U0131, U0140, U0151, U0155, U0164

DTC Code DTC Name
U0100 Lost Communication with ECM / PCM "A"
U0121 Lost Communication with Anti-lock Brake System (ABS) Control Module
U0126 Lost Communication with Steering Angle Sensor Module
U0131 Lost Communication with Electric Power Steering ECU
U0140 Lost Communication with Main Body ECU
U0151 Lost Communication with Airbag ECU
U0155 Lost Communication with Instrument Panel Cluster Control Module (Combination Meter)
U0164 Lost Communication with HVAC Control Module

DESCRIPTION

The engine stop and start ECU communicates with the SFI system, VSC system, power steering system, meter/gauge system, air conditioning system, TOYOTA parking assist-sensor system, airbag system and main body ECU (multiplex network body ECU) via CAN communication.

If an error occurs in communication between the engine stop and start ECU and any of the systems, the engine stop and start ECU stores DTCs and illuminates the stop and start cancel indicator light except when there is a communication error with the meter/gauge system.

Tech Tips


  • When there is an open in the output side of the backup boost converter (built-into the engine stop and start ECU), power to the system with an open circuit is cut off. The engine stop and start ECU stores CAN communication DTCs for the system with an open circuit and stop and start system DTC P323B.

  • When the backup boost converter (built-into the engine stop and start ECU) detects overcurrent in any of the circuits it supplies power to, it shuts off the circuit. The engine stop and start ECU stores CAN communication DTCs for the system which circuit was shutoff and stores stop and start system DTC B22C0.

    e.g.: When the backup boost converter (built into the engine stop and start ECU) detects overcurrent in the power source circuit of the power steering system and cuts off power supply, the engine stop and start ECU stores DTC U0131 and DTC B22C0.

DTC No. DTC Detection Condition Trouble Area
U0100 No communication between the engine stop and start ECU and the ECM for 0.8 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • ECM
U0121 No communication between the engine stop and start ECU and the skid control ECU for 2.3 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • Skid control ECU (brake actuator assembly)
U0126 No communication between the engine stop and start ECU and spiral with sensor cable subassembly for 0.72 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • Spiral cable with sensor sub-assembly
U0131 No communication between the engine stop and start ECU and the power steering ECU for 0.8 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • Power steering ECU
U0140 No communication between the engine stop and start ECU and the main body ECU for 3.6 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • Main body ECU (Multiplex network body ECU)
U0151 No communication between the engine stop and start ECU and the airbag sensor assembly for 10.6 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • Airbag sensor assembly
U0155 No communication between the engine stop and start ECU and the combination meter for 10.6 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • Combination meter
U0164 No communication between the engine stop and start ECU and the A/C amplifier for 10.6 seconds.

  • Wire harness or connector

  • Engine stop and start ECU

  • A/C amplifier

CAUTION / NOTICE / HINT

Tech Tips

If any of CAN communication system DTCs and sensor malfunction DTCs related to the CAN communication system are output simultaneously, perform troubleshooting for the CAN communication system DTCs first, then for the sensor malfunction DTCs.

PROCEDURE


  1. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Stop and Start / Trouble Codes.

    5. Clear the DTCs Click here.


    NEXT

  2. CHECK DTC OUTPUT


    1. Turn the ignition switch off and wait for 30 seconds or more.

    2. Turn the ignition switch to ON.

    3. Start the engine.

    4. Perform a road test.

    5. Enter the following menus: Powertrain / Stop and Start / Trouble Codes.

    6. Read the DTCs Click here.

      Result
      Result Proceed to
      DTC U0100, U0121, U0126, U0131, U0140, U0151, U0155 or U0164 is output*1 A
      DTC U0100, U0121, U0126, U0131, U0140, U0151, U0155 or U0164 is output*2 B
      DTC U0100, U0121, U0126, U0131, U0140, U0151, U0155 or U0164 is not output C

      • 1: w/o Toyota Safety Sense

      • 2: w/ Toyota Safety Sense


    A

    GO TO CAN COMMUNICATION SYSTEM Click here

    B

    GO TO CAN COMMUNICATION SYSTEM Click here

    C

    USE SIMULATION METHOD TO CHECK Click here