Toyota Yaris: 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.
If the airflow volume is low or the blower speed cannot be changed, the following factors may be the cause.
| Symptom | Factor |
|---|---|
| Airflow volume cannot be changed |
|
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 GTS (BLOWER LEVEL) |
(a) Perform the Active Test according to the display on the GTS.
Body Electrical > Air Conditioner > Active Test| Tester Display | Measurement Item | Control Range | Diagnostic Note |
|---|---|---|---|
| Blower Level | Blower motor with fan sub-assembly | Min.: 0 Max.: 31 | - |
| Tester Display |
|---|
| Blower Level |
| Result | Proceed to |
|---|---|
| Blower motor with fan sub-assembly does not operate | A |
| Blower motor with fan sub-assembly operates but does not change speed | B |
| B |
 | GO TO STEP 7 |
|
| 2. | CHECK HARNESS AND CONNECTOR (BLOWER MOTOR WITH FAN SUB-ASSEMBLY - POWER SOURCE) |
(a) Disconnect the blower motor with fan sub-assembly connector.
| (b) Measure the voltage according to the value(s) in the table below. Standard Voltage:
|
|
| NG |
 | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 3. | CHECK HARNESS AND CONNECTOR (BLOWER MOTOR WITH FAN SUB-ASSEMBLY - BODY GROUND) |
(a) Measure the resistance according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| H28-1 (GND) - Body ground | Always | Below 1 Ω |
| NG |
 | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. | CHECK HARNESS AND CONNECTOR (BLOWER MOTOR WITH FAN SUB-ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY) |
(a) Disconnect the H24 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 |
|---|---|---|
| H28-2 (SI) - H24-21 (BLW) | Always | Below 1 Ω |
| H28-2 (SI) or H24-21 (BLW) - Other terminals and body ground | Always | 10 kΩ or higher |
| NG |
 | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 5. | INSPECT BLOWER MOTOR WITH FAN SUB-ASSEMBLY |
(a) Connect the H28 blower motor with fan sub-assembly connector.
| (b) Measure the voltage according to the value(s) in the table below. Standard Voltage:
|
|
| NG |
 | REPLACE BLOWER MOTOR WITH FAN SUB-ASSEMBLY |
|
| 6. | INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY |
| *a | Component with harness connected (Air Conditioning Amplifier Assembly) |
(a) Connect the H24 air conditioning amplifier assembly connector.
(b) Using an oscilloscope, check the waveform.
| Item | Content |
|---|---|
| Terminal No. | H24-21 (BLW) - H24-17 (GND) |
| Tool Setting | 2 V/DIV., 1 ms./DIV. |
| Condition |
|
OK:
Waveform is similar to that shown in the illustration.
HINT:
The waveform varies with the blower speed.
| OK |
 | REPLACE BLOWER MOTOR WITH FAN SUB-ASSEMBLY |
| NG |
 | REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY |
| 7. | INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY |
| *a | Component with harness connected (Air Conditioning Amplifier Assembly) |
(a) Using an oscilloscope, check the waveform.
| Item | Content |
|---|---|
| Terminal No. | H24-21 (BLW) - H24-17 (GND) |
| Tool Setting | 2 V/DIV., 1 ms./DIV. |
| Condition |
|
OK:
Waveform is similar to that shown in the illustration.
HINT:
The waveform varies with the blower speed.
| OK |
 | REPLACE BLOWER MOTOR WITH FAN SUB-ASSEMBLY |
| NG |
 | REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY |
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Liftgate/Trunk Lid
WARNING
Never allow a person to ride in the luggage compartment/trunk
Allowing a person to ride in the luggage compartment/trunk is dangerous. The person in the luggage compartment/trunk could be seriously injured or killed during sudden braking or a collision.
Do not drive with the liftgate/trunk lid open
