DTC B2789: No Response from ID BOX [06/2018 - ]: Procedure

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2024 Lexus ES 300h, 2023 Lexus ES 300h, 2022 Lexus ES 300h, 2021 Lexus ES 300h, and 2020 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.

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

Disconnect the G47 certification ECU (smart key ECU assembly) connector.
Disconnect the G52 ID code box (immobiliser code ECU) connector.

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

NOTE:

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G47-13 (LIN) - G52-2 (LIN1)	Power switch off	Below 1 Ω
G47-13 (LIN) or G52-2 (LIN1) - Body ground	Power switch off	10 kΩ or higher

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

See step 2

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

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

Standard Voltage

Tester Connection	Condition	Specified Condition
G52-1 (+B) - G52-5 (GND)	Power switch off	11 to 14 V

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G52-5 (GND) - Body ground	Always	Below 1 Ω

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

See step 3

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

Replace the ID code box (immobiliser code ECU).

Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]

Result

Proceed to
NEXT

Result:

See step 4

Refer to REGISTRATION [06/2018 - 10/2019] , or refer to REGISTRATION [10/2019 - 09/2022] , or refer to REGISTRATION [09/2022 - ]

Result

Proceed to
NEXT

Result:

See step 5

CHECK FOR DTC

Clear the DTCs.
Refer to DTC CHECK / CLEAR [06/2018 - ]

Body Electrical > Smart Access > Clear DTCs

Recheck for DTCs.

Body Electrical > Smart Access > Trouble Codes

DTC B2789 is not output.

Result

Proceed to
OK
NG

Result:

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

Result:

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)