Defroster Door Motor Circuit

DEFROSTER DOOR MOTOR CIRCUIT


Defroster Door Motor Diagnosis Procedure

Regarding Wiring Diagram information, Electrical Diagrams.

SYMPTOM:
- Defroster door does not change.
- Defroster door motor does not operate normally.
1.CHECK DEFROSTER DOOR MOTOR POSITION BALANCED RESISTOR (PBR) FEEDBACK VOLTAGE
1. Turn ignition switch ON.
2. Using CONSULT-III, check "DEF FDBCK" in "DATA MONITOR" mode in "HVAC". CONSULT-III Function,
"CONSULT-III Function (HVAC)".
3. Observe "DEF FDBCK" voltage while cycling A/C auto amp mode switch through all modes and pressing
DEF switch.





Is the inspection result normal?
YES - - Defroster door motor is OK.
- Inspect defroster door for mechanical failure. Components.
NO - GO TO 2.
2.CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR OPEN AND SHORT TO GROUND





1. Turn ignition switch OFF.
2. Disconnect the A/C auto amp. harness connector M49 (A) and the defroster door motor harness connector M144 (B).
3. Check continuity between A/C auto amp. harness connector
M49 (A) terminals 23, 24 and the defroster door motor harness connector M144 (B) terminals 1, 6.










4. Check continuity between A/C auto amp. harness connector
M49 terminals 23, 24 and ground.





Is the inspection result normal?
YES - GO TO 3.
NO - Repair or replace harness as necessary.
3.CHECK A/C AUTO AMP. FOR DEFROSTER DOOR MOTOR POWER AND GROUND





1. Reconnect A/C auto amp. harness connector.
2. Turn ignition switch ON.






3. Press the mode switch to the VENT ( ) mode.
4. Check voltage between A/C auto amp. harness connector M49 terminal 23 and terminal 24 while pressing the defroster switch
( ).






Is the inspection result normal?
YES - GO TO 4.
NO - Replace A/C auto amp. Service and Repair.
4.CHECK DEFROSTER DOOR MOTOR PBR CIRCUITS FOR OPEN AND SHORT TO GROUND





1. Turn ignition switch OFF.
2. Disconnect the A/C auto amp. harness connectors M49 (C) and
M50 (A).
3. Check continuity between A/C auto amp. harness connector
M49 (C) terminal 3, and M50 (A) terminal 28 and the defroster door motor harness connector M144 (B) terminals 2, 3.






4. Check continuity between A/C auto amp. harness connector M49 (C) terminal 3, M50 (A) terminal 28 and ground.





Is the inspection result normal?
YES - GO TO 5.
NO - Repair or replace harness as necessary.
5.CHECK PBR FEEDBACK SIGNAL CIRCUIT FOR OPEN AND SHORT TO GROUND





1. Check continuity between A/C auto amp. harness connector
M49 (A) terminal 10 and defroster door motor harness connector M144 (B) terminal 4.










2. Check continuity between A/C auto amp. harness connector
M49 terminal 10 and ground.





Is the inspection result normal?
YES - GO TO 6.
NO - Repair or replace harness as necessary.
6.CHECK A/C AUTO AMP. FOR 5 VOLT REFERENCE (VREF), VREF RETURN, AND FEEDBACK SIGNAL





1. Reconnect A/C auto amp. harness connectors.
2. Turn ignition switch ON.
3. Check voltage between A/C auto amp. harness connector M49
(B) terminal 3, and M50 (A) terminal 28.










4. Check voltage between A/C auto amp. harness connector M49 terminal 10 and ground.





Is the inspection result normal?
YES - GO TO 7.
NO - Replace A/C auto amp. Service and Repair, "Removal and
Installation".
7.CHECK A/C AUTO AMP. FOR FEEDBACK SIGNAL





1. Reconnect the defroster door motor harness connector M144.
2. Check voltage between A/C auto amp. harness connector M49 terminal 10 and ground.





Is the inspection result normal?
YES - Inspect defroster door for binding or mechanical failure.
If defroster door moves freely, replace A/C auto amp.
Service and Repair.
NO - Replace the defroster door motor. Removal And Installation, "Removal and Installation".