Toyota 4Runner: Blower Motor Circuit

Toyota 4Runner Service Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System(for Automatic Air Conditioning System) / Blower Motor Circuit

DESCRIPTION

The blower with fan motor sub-assembly operates according to signals from the air conditioning amplifier assembly. The blower with fan motor sub-assembly speed signals are transmitted by changes in the duty ratio.

Duty Ratio:

The duty ratio is the ratio of the blower with fan motor sub-assembly on time (T1) to the total of the blower with fan motor sub-assembly on and off time (T2).

The air conditioning amplifier assembly controls the blower with fan motor sub-assembly speed.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.	PERFORM ACTIVE TEST USING TECHSTREAM (BLOWER WITH FAN MOTOR)

(a) Select the Active Test, use the Techstream to generate a control command, and then check that the blower with fan motor sub-assembly operates (See page ).

Air Conditioner

Tester Display	Test Part	Control Range	Diagnostic Note
Blower Motor	Blower with fan motor sub-assembly	Min.: 0, Max.: 31	-

OK:

Blower with fan motor sub-assembly operates and blower motor speed changes.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	CHECK HARNESS AND CONNECTOR (BLOWER WITH FAN MOTOR - BATTERY AND BODY GROUND)

(a) Disconnect the F43 motor connector.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
F43-3 (+B) - Body ground	Always	11 to 14 V

Standard Resistance:

Tester Connection	Condition	Specified Condition
F43-1 (GND) - Body ground	Always	Below 1 Ω

Text in Illustration

*a	Front view of wire harness connector (to Blower with Fan Motor Sub-assembly)

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.	CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BLOWER WITH FAN MOTOR AND BODY GROUND)

(a) Disconnect the F42 amplifier connector.

(b) Disconnect the F43 motor connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F42-23 (BLW) - F43-2 (SI)	Always	Below 1 Ω
F42-23 (BLW) - Body ground	Always	10 kΩ or higher
F42-14 (GND) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (BLW SIGNAL)

(a) Remove the air conditioning amplifier assembly with its connectors still connected (See page ).

(b) Using an oscilloscope, check the waveform.

Measurement Condition

Item	Content
Terminal No. (Symbol)	F42-23 (BLW) - F42-14 (GND)
Tool Setting	1 V/DIV., 500 μs/DIV.
Condition	Ignition switch ON Blower switch LO

Item

Content

Terminal No. (Symbol)

F42-23 (BLW) - F42-14 (GND)

Tool Setting

1 V/DIV., 500 μs/DIV.

Condition

Ignition switch ON

Blower switch LO

OK:

Waveform is as shown in the illustration.

Text in Illustration

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

HINT:

Waveform varies with the blower level.

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

5.	REPLACE BLOWER WITH FAN MOTOR SUB-ASSEMBLY

(a) Replace the blower with fan motor sub-assembly with a new or normally functioning one (See page ).

(b) Operate the blower with fan motor sub-assembly to check that it functions properly.

OK:

Blower with fan motor sub-assembly operates normally.

END (BLOWER WITH FAN MOTOR SUB-ASSEMBLY IS FAULTY)

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