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

DESCRIPTION

The rear blower motor with fan sub-assembly is operated by signals from the air conditioning amplifier assembly. Rear 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) Check the operation by referring to the table below.

Body Electrical > Air Conditioner > Active Test

Tester Display

Measurement Item

Control Range

Diagnostic Note

Rear Blower Motor

Rear blower motor with fan sub-assembly

Min.: 0

Max.: 31

-

Body Electrical > Air Conditioner > Active Test

Tester Display

Rear Blower Motor

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROL - POWER SOURCE AND BODY GROUND)

(a) Disconnect the R51 blower motor control connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

R51-1 (+B) - Body ground

Always

11 to 14 V

Standard Resistance:

Tester Connection

Condition

Specified Condition

R51-6 (GND) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.

CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROL - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the J48 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

R51-3 (SI) - J48-12 (BLWH)

Always

Below 1 Ω

R51-3 (SI) or J48-12 (BLWH) - Other terminals and body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

R50-2 (+) - R51-2 (VM)

Always

Below 1 Ω

R50-1 (-) - Body ground

Always

Below 1 Ω

R50-2 (+) or R51-2 (VM) - Other terminals and body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

5.

INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY

*a

Component with harness connected

(Blower Motor Control)

(a) Connect the J48 air conditioning amplifier assembly connector.

(b) Measure the waveform.

OK:

Waveform is similar to that shown in the illustration.

Item

Content

Terminal No.

R51-3 (SI) - Body ground

Tool Setting

2 V/DIV., 500 μs./DIV.

Vehicle Condition

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

HINT:

The waveform varies with the blower level.

NG

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

OK

6.

INSPECT REAR BLOWER MOTOR WITH FAN SUB-ASSEMBLY

(a) Remove the rear blower motor with fan sub-assembly connector.

Click here

(b) Inspect the rear blower motor with fan sub-assembly connector.

Click here

OK

REPLACE BLOWER MOTOR CONTROL

NG

REPLACE REAR BLOWER MOTOR WITH FAN SUB-ASSEMBLY

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