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 or Techstream to generate a control command, and then check that the rear blower motor operates.

Air Conditioner





Result





C -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - REAR AIR CONDITIONING HARNESS)
B -- INSPECT FUSE (RR A/C)
A -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
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 according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE FUSE
OK -- Continue to next step.
3.
CHECK HARNESS AND CONNECTOR (REAR AIR CONDITIONING HARNESS - BODY GROUND)




(a) Disconnect the S28 rear air conditioning harness 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 AIR CONDITIONING HARNESS - BATTERY)




(a) Disconnect the S28 rear air conditioning harness 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 AIR CONDITIONING HARNESS (SI VOLTAGE)




(a) Disconnect the L76 air conditioning amplifier connector.
(b) Reconnect the S28 rear air conditioning harness connector.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPLACE REAR AIR CONDITIONING HARNESS
OK -- Continue to next step.
6.
CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - REAR AIR CONDITIONING HARNESS)




(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) Using an oscilloscope, check the waveform.

Measurement condition





OK:
Waveform is as shown in the illustration.
HINT: Waveform varies with the blower level.

NG -- REPLACE AIR CONDITIONING AMPLIFIER
OK -- Continue to next step.
8. REPLACE REAR AIR CONDITIONING HARNESS
(a) Replace the rear air conditioning harness with a normal one and check that the condition returns to normal Disassembly.
OK:
Same problem does not occur.
NG -- REPLACE REAR BLOWER MOTOR
OK -- END (REAR AIR CONDITIONING HARNESS IS DEFECTIVE)