Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: No Response from ID BOX (B2789)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Power Source & Network / Networking / Lin Communication System / No Response from ID BOX (B2789)

DESCRIPTION

This DTC is stored when LIN communication between the certification ECU (smart key ECU assembly) and ID code box (immobiliser code ECU) stops for 10 seconds or more.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B2789

No Response from ID BOX

No communication between certification ECU (smart key ECU assembly) and ID code box (immobiliser code ECU) for 10 seconds or more.
  • ID code box (immobiliser code ECU)
  • Certification ECU (smart key ECU assembly)
  • Wire harness or connector
  • ECU-B NO. 3 fuse

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • If the certification ECU (smart key ECU assembly) or ID code box (immobiliser code ECU) is replaced, refer to Registration.

    Click here

  • 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 Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Smart Access(CAN). 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.

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ID CODE BOX (IMMOBILISER CODE ECU))

(a) Disconnect the J41 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the J36 ID code box (immobiliser code ECU) connector.

(c) Measure the resistance according to the value(s) in the table below.

NOTICE:

Make sure that each ECU is in sleep mode before performing the inspection. To enter sleep mode, turn the engine switch from on (IG) to off and wait for 180 seconds or more without operating any switches.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J41-13 (LIN) - J36-2 (LIN1)

Engine switch off

Below 1 Ω

J41-13 (LIN) or J36-2 (LIN1) - Body ground

Engine switch off

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

2.

CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - BATTERY, BODY GROUND)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

J36-1 (+B) - J36-5 (GND)

Always

11 to 14 V

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J36-5 (GND) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

(a) Replace the ID code box (immobiliser code ECU).

Click here

NEXT

4.

REGISTER ECU CODE REGISTRATION

(a) Register the recognition codes in the ECUs.

HINT:

Refer to Registration.

Click here

NEXT

5.

CHECK FOR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Smart Access > Clear DTCs

(b) Recheck for DTCs.

Body Electrical > Smart Access > Trouble Codes

OK:

DTC B2789 is not output.

OK

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

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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