Back-up Light Circuit [08/2020 - ]: 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 FOR DTC

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Enter the following menus: Powertrain / Hybrid Control / Trouble Codes.

Check for DTCs.

Powertrain > Hybrid Control > Trouble Codes

Result

Result	Proceed to
Hybrid control system DTCs are not output	A
Hybrid control system DTCs are output	B

Result:

GO TO HYBRID CONTROL SYSTEM

for NICKEL METAL HYDRIDE BATTERY: Refer to DIAGNOSTIC TROUBLE CODE CHART [06/2018 - 08/2021] , or refer to DIAGNOSTIC TROUBLE CODE CHART [08/2021 - ]

for LITHIUM-ION BATTERY: Refer to DIAGNOSTIC TROUBLE CODE CHART [08/2020 - 08/2021] , or refer to DIAGNOSTIC TROUBLE CODE CHART [08/2021 - ]

Result:

See step 2

CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - BODY GROUND)

Disconnect the 3D instrument panel junction block assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
3D-3 - Body ground	Always	Below 1 Ω

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

See step 3

CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

Disconnect the A33 hybrid vehicle control ECU connector.
Disconnect the 3F instrument panel junction block assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A33-2 (BL) - 3F-19	Always	Below 1 Ω
A33-2 (BL) or 3F-19 - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

See step 4

CHECK HYBRID VEHICLE CONTROL ECU (OUTPUT VOLTAGE)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Component with harness connected (Instrument Panel Junction Block Assembly)

Connect the A33 hybrid vehicle control ECU connector.
Connect the 3D and 3F instrument panel junction block assembly connectors.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
3F-19 - Body ground	Power switch off, reverse (R) not selected	Below 1 V
3F-19 - Body ground	Power switch on (IG), reverse (R) selected	11 to 14 V

Result

Proceed to
OK
NG

Result:

REPLACE HYBRID VEHICLE CONTROL ECU. Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]

Result:

See step 5

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (OUTPUT VOLTAGE)

*a	Component with harness connected (Instrument Panel Junction Block Assembly)

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

Standard Voltage

Tester Connection	Condition	Specified Condition
3H-10 - Body ground	Power switch off, reverse (R) not selected	Below 1 V
3H-10 - Body ground	Power switch on (IG), reverse (R) selected	11 to 14 V

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]