Rear Blower Motor Circuit

AIR CONDITIONING: AIR CONDITIONING SYSTEM: Rear Blower Motor Circuit
- Rear Blower Motor Circuit

DESCRIPTION





The rear blower motor is operated by signals from the air conditioning amplifier. Rear blower motor speed signals are transmitted by changes in the duty ratio.

Duty Ratio:

The duty ratio is the ratio of the rear blower motor ON time (A) to the total of the rear blower motor ON and OFF time (A + B).

The rear blower motor controller controls the rear blower motor speed.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (REAR BLOWER MOTOR)

(a) Select the Active Test, using the Techstream to generate a control command, and then check that the rear blower motor operates.

Air Conditioner





Result





C -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

B -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - REAR BLOWER MOTOR)
A -- Continue to next step.

2. INSPECT FUSE (RR A/C)

(a) Remove the RR A/C H-fuse from the engine room No. 1 relay block.

(b) Measure the resistance of the fuse.

Standard resistance:





NG -- REPLACE FUSE
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (REAR BLOWER MOTOR - BODY GROUND)





(a) Disconnect the rear blower motor connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (REAR BLOWER MOTOR - BATTERY)





(a) Disconnect the rear blower motor connector.

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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

5. CHECK REAR BLOWER MOTOR (SI VOLTAGE)





(a) Disconnect the rear blower motor connector.

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

Standard voltage:





NG -- CHECK HARNESS AND CONNECTOR (REAR BLOWER MOTOR - AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - REAR BLOWER MOTOR)





(a) Disconnect the L76 air conditioning amplifier connector.

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

Standard voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

7. CHECK AIR CONDITIONING AMPLIFIER (SBLW SIGNAL)

(a) Remove the air conditioning amplifier with its connectors still connected Removal.





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

(c) Turn the rear blower switch ON (Lo).

(d) Using an oscilloscope, check the waveform.

Waveform (Reference):





OK:

Waveform is as shown in the illustration.

HINT
Waveform varies with the blower level.

NG -- REPLACE AIR CONDITIONING AMPLIFIER Removal

OK -- REPLACE REAR BLOWER MOTOR Disassembly

8. CHECK HARNESS AND CONNECTOR (REAR BLOWER MOTOR - AIR CONDITIONING AMPLIFIER)





(a) Disconnect the L76 air conditioning amplifier connector.

(b) Disconnect the rear blower motor connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE REAR BLOWER MOTOR Disassembly