Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Open / Short in Steering Lock ECU (B2781)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Suspension / Steering Column / Steering Lock System / Open / Short in Steering Lock ECU (B2781)

DESCRIPTION

The steering lock ECU and steering lock motor are built into the steering lock actuator or upper bracket assembly.

The steering lock ECU (steering lock actuator or upper bracket assembly) detects whether the steering lock is in the lock or unlock position by using the lock sensor and unlock sensor of the steering lock motor.

The steering lock ECU (steering lock actuator or upper bracket assembly) receives lock and unlock request signals from the certification ECU (smart key ECU assembly) and responds with lock and unlock operation signals.

HINT:

The steering lock ECU (steering lock actuator or upper bracket assembly) is not connected to the CAN communication system. However, the steering lock ECU (steering lock actuator or upper bracket assembly) is connected to the certification ECU (smart key ECU assembly) via LIN communication and communicates with other components via CAN communication through the certification ECU (smart key ECU assembly).

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2781

Open / Short in Steering Lock ECU

One of the following conditions is met (1-trip detection logic (Only output while a malfunction is present and the engine switch is on (IG).)):

  • The steering lock sensor or unlock sensor is malfunctioning (When both detection switches turn on, the system is determined to be malfunctioning).
  • The steering lock motor activation circuit has a short circuit.
  • The steering lock motor activation circuit has an open circuit.
  • Steering lock ECU (steering lock actuator or upper bracket assembly)
  • LIN communication system

DTC Output Confirmation Operation: No confirmation operation is necessary (monitoring is continuous).
Vehicle Condition and Fail-safe Function when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Function when Malfunction Detected

The steering cannot be locked or unlocked. For this reason, the engine cannot be started.

Prohibits the engine from being started (the engine does not crank).
Related Data List and Active Test Items

DTC No.

Data List Item

Active Test Item

B2781
Smart Access
  • Sensor Value
  • Motor Driver Short

-

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the engine switch off, connect the Techstream to the vehicle and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the Techstream and the vehicle begins. Then select the Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Smart Access. While using the Techstream, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the Techstream and the vehicle.
  • After performing repairs, confirm that no DTCs are output again.

    Click here

  • When replacing the steering lock ECU (steering lock actuator or upper bracket assembly), registration must be performed.

    Click here

HINT:

When all the ECUs that are connected via LIN communication cannot communicate with the certification ECU (smart key ECU assembly), DTC B2785 is stored.

PROCEDURE

1.

CHECK DTC

(a) Using the Techstream, check if LIN communication DTC B2785 is output.

Click here

HINT:

If a LIN communication DTC is output, perform troubleshooting for the LIN communication system.

Click here

Result

Proceed to

DTC B2785 is output.

A

DTC B2785 is not output.

B
A

GO TO LIN COMMUNICATION SYSTEM (DTC B2785)

B

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPPER BRACKET ASSEMBLY)

    Steering Lock System
    ...

    Power Source Control ECU Malfunction (B2782)
    DESCRIPTION The certification ECU (smart key ECU assembly) has a power source mode switching function. This DTC is stored when the IGE input (the steering lock motor activation permission signal) sent ...

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