Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Blower Motor Circuit

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / Blower Motor Circuit

DESCRIPTION

The blower motor with fan sub-assembly is operated by signals from the air conditioning amplifier assembly. Blower motor speed signals are transmitted in accordance with changes in the duty ratio.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

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

Blower Motor

Blower motor with fan sub-assembly

Min.: 0, Max.: 31

-
Body Electrical > Air Conditioner > Active Test

Tester Display

Blower Motor

Result

Proceed to

OK

A

NG (Blower motor with fan sub-assembly does not operate)

B

NG (Blower motor with fan sub-assembly operates but does not change speed)

C
A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

GO TO STEP 6

B

2.

CHECK HARNESS AND CONNECTOR (BLOWER MOTOR WITH FAN SUB-ASSEMBLY - BODY GROUND)

(a) Disconnect the A16 blower motor with fan sub-assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A16-1 (GND) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK HARNESS AND CONNECTOR (BLOWER MOTOR WITH FAN SUB-ASSEMBLY - BATTERY)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A16-3 (+B) - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - BLOWER MOTOR WITH FAN SUB-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

J43-6 (BLW) - A16-2 (SI)

Always

Below 1 Ω

J43-6 (BLW) or A16-2 (SI) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

5.

INSPECT BLOWER MOTOR WITH FAN SUB-ASSEMBLY

(a) Reconnect the A16 blower motor with fan sub-assembly connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

J43-6 (BLW) - Body ground

Always

4.75 to 5.25 V

*a

Front view of wire harness connector

(to Air Conditioning Amplifier Assembly)
NG

REPLACE BLOWER MOTOR WITH FAN SUB-ASSEMBLY

OK

6.

INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY

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

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

(c) Turn the blower switch on (LO).

(d) Measure the waveform between terminals J43-6 (BLW) and J43-4 (GND) of the air conditioning amplifier assembly.

OK:

Waveform is similar to that shown in the illustration.

HINT:

The waveform varies with the blower speed.

Item

Content

Tool Setting

2 V/DIV., 1 ms./DIV.

Vehicle Condition
  • Engine switch on (IG)
  • Blower switch: LO

*a

Component with harness connected

(Air Conditioning Amplifier Assembly)
OK

REPLACE BLOWER MOTOR WITH FAN SUB-ASSEMBLY

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

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