Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Mirror Heater does not Operate with Rear Defogger Switch

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Exterior / Mirror (ext) / Power Mirror Control System (w/o Memory) / Mirror Heater does not Operate with Rear Defogger Switch

DESCRIPTION

When the mirror heater switch (rear window defogger switch) is operated, the mirror heater signal is sent to the air conditioning amplifier assembly and then to each outer mirror control ECU assembly via CAN communication. Based on this signal, the outer mirror control ECU assemblies operate the mirror heaters.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • The power mirror control system (w/o Memory) uses the CAN communication system. First, confirm that there is no malfunction in the CAN communication system. Refer to the How to Proceed with Troubleshooting procedure.

    Click here

  • If the battery voltage is low, the mirror heater function may not operate. When "Operation of Electrical Items Restricted." is not displayed on the multi-information display in the combination meter assembly, check the Data List item "Battery Control Count (Body ECU)".

    Click here

  • Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

    Click here

PROCEDURE

1.

CHECK WINDOW DEFOGGER SYSTEM

(a) Check window defogger system operation.

Click here

OK:

Window defogger system is normal.

NG

GO TO WINDOW DEFOGGER SYSTEM

OK

2.

PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Mirror L or Mirror R / Active Test.

(e) Perform an Active Test according to the display on the Techstream.

Body Electrical > Mirror L > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Mirror Heater

Mirror heater operation

OFF or ON
  • Operate with the engine switch on (IG) and the vehicle stopped.
  • This test turns the mirror heater on or off.
  • Mirror heater operation can be confirmed by touch.
Body Electrical > Mirror L > Active Test

Tester Display

Mirror Heater
Body Electrical > Mirror R > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Mirror Heater

Mirror heater operation

OFF or ON
  • Operate with the engine switch on (IG) and the vehicle stopped.
  • This test turns the mirror heater on or off.
  • Mirror heater operation can be confirmed by touch.
Body Electrical > Mirror R > Active Test

Tester Display

Mirror Heater

Result

Proceed to

Mirror heater operation on both mirrors is normal

A

Mirror heater operation on driver door mirror is not normal

B

Mirror heater operation on front passenger door mirror is not normal

C
A

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

C

GO TO STEP 5

B

3.

INSPECT OUTER REAR VIEW MIRROR ASSEMBLY (DRIVER DOOR) (MIRROR HEATER)

(a) Remove the outer rear view mirror assembly (driver door).

Click here

(b) Remove the outer rear view mirror assembly (driver door) (mirror heater).

Click here

OK

REPLACE OUTER MIRROR CONTROL ECU ASSEMBLY (DRIVER DOOR)

NG

4.

INSPECT OUTER MIRROR (DRIVER DOOR)

(a) Remove the outer mirror (driver door).

Click here

(b) Inspect the outer mirror (driver door).

Click here

OK

REPLACE OUTER REAR VIEW MIRROR ASSEMBLY (DRIVER DOOR)

NG

REPLACE OUTER MIRROR (DRIVER DOOR)

5.

INSPECT OUTER REAR VIEW MIRROR ASSEMBLY (FRONT PASSENGER DOOR) (MIRROR HEATER)

(a) Remove the outer rear view mirror assembly (front passenger door).

Click here

(b) Remove the outer rear view mirror assembly (front passenger door) (mirror heater).

Click here

OK

REPLACE OUTER MIRROR CONTROL ECU ASSEMBLY (FRONT PASSENGER DOOR)

NG

6.

INSPECT OUTER MIRROR (FRONT PASSENGER DOOR)

(a) Remove the outer mirror (front passenger door).

Click here

(b) Inspect the outer mirror (front passenger door).

Click here

OK

REPLACE OUTER REAR VIEW MIRROR ASSEMBLY (FRONT PASSENGER DOOR)

NG

REPLACE OUTER MIRROR (FRONT PASSENGER DOOR)

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