Lexus RX (RX 350L, RX450h) 2016-2024 Repair Manual: Rear Window Defogger System does not Operate

DESCRIPTION

When the rear window defogger switch on the radio receiver assembly is pressed, the operation signal is transmitted to the air conditioning amplifier assembly via CAN communication. When the air conditioning amplifier assembly receives the signal, it turns on the semiconductor pwr integration ECU to operate the window defogger system.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

1.	CHECK AIR CONDITIONING SYSTEM

(a) Check the air conditioning system.

HINT:

Both the window defogger system operation signal and air conditioning system operation signal are transmitted to the air conditioning amplifier assembly through the same communication line.

OK:

The air conditioning system operates normally.

NG

GO TO AIR CONDITIONING 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 / Air Conditioner / Active Test.

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

Body Electrical > Air Conditioner > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Defogger Relay (Rear)	Rear window defogger wire (back window glass)	OFF or ON	-

Body Electrical > Air Conditioner > Active Test

Tester Display
Defogger Relay (Rear)

OK:

The rear window defogger system operates normally.

NG

GO TO STEP 4

OK

3.	REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Replace the air conditioning amplifier assembly with a new or known good one.

Click here

(b) Check that the window defogger system operates normally.

Click here

OK:

The window defogger system operates normally.

OK

END (AIR CONDITIONING AMPLIFIER ASSEMBLY WAS DEFECTIVE)

NG

REPLACE RADIO RECEIVER ASSEMBLY

4.	CHECK SEMICONDUCTOR POWER INTEGRATION ECU

(a) Using a voltmeter, check the signal reading of the semiconductor pwr integration ECU.

Click here

OK:

Output signal reading is normal.

NG

INSPECT SEMICONDUCTOR POWER INTEGRATION ECU (RESULTS OF SIGNAL READING CHECK)

OK

5.	CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR PWR INTEGRATION ECU POWER SOURCE AND BODY GROUND)

(a) Remove the semiconductor pwr integration ECU from the engine room relay block.

Click here

*a

Component without semiconductor pwr integration ECU (Engine Room Relay Block)

-

-

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
B-1 (BATT) - Body ground	Always	11 to 14 V
A-1 (ALT) - Body ground	Always	11 to 14 V

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
1D-14 (GND1) - Body ground	Always	Below 1 Ω
1G-5 (GND2) - Body ground	Always	Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.	CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR PWR INTEGRATION ECU - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the J43 air conditioning amplifier assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
J43-5 (RDFG) - 1D-5 (-S)	Always	Below 1 Ω
J43-5 (RDFG) or 1D-5 (-S) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

7.	CHECK SEMICONDUCTOR POWER INTEGRATION ECU

(a) Install the semiconductor pwr integration ECU.

Click here

(b) Measure the voltage according to the value(s) in the table below. Standard Voltage: Tester Connection Condition Specified Condition J43-5 (RDFG) - Body ground Engine switch on (IG), rear window defogger switch off 11 to 14 V

*a Front view of wire harness connector (to Air Conditioning Amplifier Assembly)

NG

REPLACE SEMICONDUCTOR POWER INTEGRATION ECU

OK

8.	CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY

(a) Reconnect the J43 air conditioning amplifier assembly connector.

(b) Measure the voltage according to the value(s) in the table below. Standard Voltage: Tester Connection Condition Specified Condition J43-5 (RDFG) - J43-4 (GND) Engine switch on (IG), rear window defogger switch on Below 2.2 V J43-5 (RDFG) - J43-4 (GND) Engine switch on (IG), rear window defogger switch off 11 to 14 V

*a Component with harness connected (Air Conditioning Amplifier Assembly)

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

OK

9.	CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR PWR INTEGRATION ECU - REAR WINDOW DEFOGGER WIRE (BACK WINDOW GLASS))

(a) Disconnect the Z5 rear window defogger wire (back window glass) connector.

(b) Disconnect the 1C semiconductor pwr integration ECU connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
1C-1 (L) - Z5-1	Always	Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

10.	CHECK SEMICONDUCTOR POWER INTEGRATION ECU

(a) Reconnect the 2C semiconductor pwr integration ECU connector.

(b) Measure the voltage according to the value(s) in the table below. Standard Voltage: Tester Connection Condition Specified Condition Z5-1 - Body ground Engine switch on (IG), rear window defogger switch on 11 to 14 V Z5-1 - Body ground Engine switch on (IG), rear window defogger switch off Below 1 V

*a Front view of wire harness connector (to Rear Window Defogger Wire (Back Window Glass))

NG

REPLACE SEMICONDUCTOR POWER INTEGRATION ECU

OK

11.	CHECK HARNESS AND CONNECTOR (REAR WINDOW DEFOGGER WIRE (BACK WINDOW GLASS) - BODY GROUND)

(a) Disconnect the Z13 rear window defogger wire (back window glass) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
Z13-1 - Body ground	Always	Below 1 Ω

OK

REPAIR OR REPLACE REAR WINDOW DEFOGGER WIRE (BACK WINDOW GLASS)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR