Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual: ID BOX EEPROM Malfunction (B2790)

Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual / Vehicle Interior / Theft Deterrent / Keyless Entry / Immobiliser System / ID BOX EEPROM Malfunction (B2790)

DESCRIPTION

When an internal malfunction occurs in the ID code box (immobiliser code ECU), the certification ECU (smart key ECU assembly) stores this DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Note

B2790

ID BOX EEPROM Malfunction

An internal malfunction occurs in the ID code box (immobiliser code ECU) (EEPROM access malfunction). (1 trip detection logic*)
  • ID code box (immobiliser code ECU)
  • Certification ECU (smart key ECU assembly)

DTC output confirmation operation:

  • An immobiliser set/unset operation is performed (the engine switch is turned off or on (IG) while the key is being carried).
  • *: Only output while a malfunction is present.
Vehicle Condition and Fail-safe Operation when Malfunction Detected

Vehicle Condition when Malfunction Detected

Fail-safe Operation when Malfunction Detected
  • Engine running: Engine cannot be started next time
  • Engine stopped: Engine cannot be started

-
Related Data List and Active Test

DTC No.

Data List and Active Test

B2790

-

CAUTION / NOTICE / HINT

NOTICE:

  • When using the Techstream with the engine switch off, connect the Techstream to the DLC3 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 vehicle type 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.
  • Before replacing the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU), refer to Registration.

    Click here

  • After performing repairs, confirm that no DTCs are output by performing "DTC Output Confirmation Operation."

PROCEDURE

1.

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

(a) Replace the ID code box (immobiliser code ECU) with a new one.

Click here

NEXT

2.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Smart Access > Clear DTCs
NEXT

3.

REGISTER RECOGNITION CODE

(a) Register the recognition code to the ECUs.

Click here

NEXT

4.

REGISTER ECU COMMUNICATION ID

(a) Register the ECU communication ID codes.

Click here

NEXT

5.

CHECK FOR DTC

(a) Perform "DTC Output Confirmation Operation" procedure.

(b) Check for DTCs.

Body Electrical > Smart Access > Trouble Codes

OK:

DTC B2790 is not output.

OK

END (ID CODE BOX (IMMOBILISER CODE ECU) WAS DEFECTIVE)
NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    Antenna Coil Open / Short (B2784)
    DESCRIPTION When an open or short circuit is detected in the transponder key amplifier coil built into the engine switch, the certification ECU (smart key ECU assembly) stores this DTC. This DTC is al ...

    Engine Immobiliser System Signal (Some Circuit Quantity, Reported via Serial Data) Invalid (B279986)
    DESCRIPTION If there is a communication malfunction between the ECM and ID code box (immobiliser code ECU), or when the communication ID codes do not match, the ECM stores this DTC. DTC No. Detec ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Wiper And Washer System: Fail-safe Chart
    FAIL-SAFE CHART AUTO WIPER FAIL-SAFE FUNCTION (a) If the wiper system is malfunctioning, the windshield wiper motor and link assembly (wiper ECU) performs a fail-safe function to control the system. Item Fail-Safe Function Conditions to Return to Normal Condition Overheat protection Dec ...

    Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Front Radar Sensor System: How To Proceed With Troubleshooting
    CAUTION / NOTICE / HINT HINT: Before performing troubleshooting for the front radar sensor system, perform troubleshooting for the pre-collision system. Click here *: Use the Techstream. PROCEDURE 1. VEHICLE BROUGHT TO WORKSHOP NEXT 2. CUSTOMER PROBLEM ANALY ...

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

    © 2026 Copyright www.lexusrx.net
    0.038