INFINITI QX4 2005 Factory Service Manual

ATC-86
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
3. CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the BACK button to back out of self-diagnostic mode.
2. Check voltage between front air control harness connector M49
terminal 7 and terminal 8 while placing the HVAC system into
self-diagnostic mode.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-147, "
FRONT AIR CONTROL" .
4. CHECK INTAKE DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 7 and terminal 8.
OK or NG
OK >> Replace intake door motor. Refer to ATC-164, "Removal
and Installation" .
NG >> GO TO 5.
5. CHECK INTAKE DOOR MOTOR CIRCUITS FOR OPEN
1. Disconnect the intake door motor harness connector.
2. Check continuity between front air control harness connector
M49 terminal 7, 8 and the intake door motor harness connector
M58 terminal 1, 6.
OK or NG
OK >> Replace intake door motor. Refer to ATC-164, "Removal
and Installation" .
NG >> Repair or replace harness as necessary.
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M498 7Self-diagnostic
modeBattery
voltage
WJIA1759E
Continuity should exist.
WJIA1760E
1 - 7 : Continuity should exist.
6 - 8 : Continuity should exist.
WJIA0591E

TROUBLE DIAGNOSIS
ATC-87
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AT C
Revision: October 20052005 QX56
Defroster Door Motor CircuitEJS003XR
SYMPTOM:

Defroster door does not change.

Defroster door motor does not operate normally.
INSPECTION FLOW
*1ATC-57, "Operational Check
(Front)"*2AT C - 5 5 , "A/C System Self-diagnosis
Function"*3AT C - 5 6 , "SELF-DIAGNOSIS CODE
CHART"
WJIA1353E

ATC-88
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
SYSTEM DESCRIPTION
Component Parts
Defroster door control system components are:

Front air control

Defroster door motor

PBR (Built into defroster door motor)

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
The front air control determines defroster door position based on the position of the defroster switch. When the
defroster switch is depressed, the defroster door motor rotates directing air to the defroster ducts. When any
mode other than defroster is selected, the defroster motor rotates in the opposite direction closing off air flow
to the defroster ducts.
In the AUTO mode, the front air control determines defroster door position based on the ambient temperature,
the intake air temperature and the in-vehicle temperature.
COMPONENT DESCRIPTION
Defroster door motor
The defroster door motor is attached to the front heater & cooling
unit. The front air control sends a voltage to rotate to the defroster
door directing the air flow either to the defroster ducts, or to the floor
ducts, depending on which way the voltage and ground are applied
to the motor leads. Motor rotation is conveyed to a lever which acti-
vates the defroster door.
WJIA1354E
WJIA0592E

TROUBLE DIAGNOSIS
ATC-89
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Revision: October 20052005 QX56
DIAGNOSTIC PROCEDURE FOR DEFROSTER DOOR MOTOR
1. CHECK FRONT AIR CONTROL FOR POWER AND GROUND
1. Turn ignition switch ON.
2. Press the defroster switch ( ).
3. Check voltage between front air control harness connector M49
terminal 20 and terminal 19 and press the defroster switch ( )
again.
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 19, 20 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-147, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.
3. CHECK FRONT AIR CONTROL FOR GROUND AND POWER
1. Press the defroster switch ( ).
2. Check voltage between front air control harness connector M49
terminal 19 and terminal 20 and press the defroster switch ( )
again.
OK or NG
OK >> GO TO 4.
NG >> Replace front air control. Refer to ATC-147, "
FRONT AIR CONTROL" .
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M4920 19Press
defroster
switchBattery
voltage
WJIA1765E
19 - Ground : Continuity should not exist.
20 - Ground : Continuity should not exist.
WJIA1766E
ConnectorTerminals
Condition Voltage
(Approx.)
(+) (-)
Front air control:
M4919 20Press
defroster
switchBattery
voltage
WJIA1767E

ATC-90
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
4. CHECK DEFROSTER DOOR MOTOR AND CIRCUITS FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 19 and terminal 20.
OK or NG6
OK >> GO TO 6.
NG >> GO TO 5.
5. CHECK DEFROSTER DOOR MOTOR CIRCUITS FOR OPEN
1. Disconnect the defroster door motor harness connector.
2. Check continuity between front air control harness connector
M49 terminal 19, 20 and the defroster door motor harness con-
nector terminal 1, 6.
OK or NG
OK >> Replace defroster door motor. Refer to ATC-163,
"Removal and Installation" .
NG >> Repair or replace harness as necessary.
6. CHECK FRONT AIR CONTROL FOR PBR POWER AND GROUND
1. Reconnect front air control harness connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 2 and terminal 15.
OK or NG
OK >> GO TO 8.
NG >> GO TO 7.
7. CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 2 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-147, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.Continuity should exist.
WJIA1773E
19 - 1 : Continuity should exist.
20 - 6 : Continuity should exist.
WJIA0553E
ConnectorTe r m i n a l s
Voltage
(Approx.)
(+) (-)
Front air control: M49 2 15 5V
WJIA1729E
Continuity should not exist.
WJIA1730E

TROUBLE DIAGNOSIS
ATC-91
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AT C
Revision: October 20052005 QX56
8. CHECK PBR REFERENCE VOLTAGE AND GROUND CIRCUITS
1. Turn ignition switch OFF.
2. Disconnect the front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 2 and terminal 15.
OK or NG
OK >> GO TO 10.
NG >> GO TO 9.
9. CHECK PBR REFERENCE VOLTAGE CIRCUIT FOR OPEN
1. Disconnect the defroster door motor harness connector.
2. Check continuity between defroster door motor harness connec-
tor M144 (B) terminal 3, 2 and front air control harness connec-
tor M49 (A) terminal 2, 15.
OK or NG
OK >> Replace defroster door motor. Refer to ATC-163,
"Removal and Installation" .
NG >> Repair or replace harness as necessary.
10. CHECK PBR FEEDBACK VOLTAGE
1. Reconnect the front air control harness connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49
terminal 25 and ground while cycling defroster switch on and off.
OK or NG
OK >> GO TO 12.
NG >> GO TO 11.
11 . CHECK PBR FEEDBACK SIGNAL CIRCUIT FOR SHORT TO GROUND
1. Turn ignition switch OFF.
2. Disconnect front air control harness connector.
3. Check continuity between front air control harness connector
M49 terminal 25 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-147, "FRONT
AIR CONTROL" .
NG >> Repair or replace harness as necessary.Continuity should exist.
WJIA1731E
2 - 3 : Continuity should exist.
15 - 2 : Continuity should exist.
WJIA1777E
Voltage : Approx. 1V - 4.5V
WJIA1786E
Continuity should not exist.
WJIA1787E

ATC-92
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
12. CHECK PBR FEEDBACK CIRCUIT FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect the defroster door motor harness connector and
front air control harness connector.
3. Check continuity between defroster door motor harness connec-
tor M144 terminal 4 and front air control harness connector M49
terminal 25
OK or NG
OK >> Replace defroster door motor. Refer to ATC-163,
"Removal and Installation" .
NG >> Repair or replace harness as necessary.Continuity should exist.WJIA0558E

TROUBLE DIAGNOSIS
ATC-93
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AT C
Revision: October 20052005 QX56
Front Blower Motor CircuitEJS003XS
SYMPTOM:

Blower motor operation is malfunctioning.
INSPECTION FLOW
*1ATC-57, "Operational Check (Front)"*2AT C - 5 5 , "A/C System Self-diagnosis
Function"
*3AT C - 5 6 , "SELF-DIAGNOSIS CODE
CHART"
*4ATC-95, "DIAGNOSTIC PROCE-
DURE FOR BLOWER MOTOR"
*5EC-195, "DTC P0117, P0118 ECT
SENSOR"
*6AT C - 3 8 , "SYMPTOM TABLE"
WJIA1251E

ATC-94
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
SYSTEM DESCRIPTION
Component Parts
Blower speed control system components are:

Front air control

Front blower motor

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
Automatic Mode
In the automatic mode, the blower motor speed is calculated by the front air control and variable blower control
based on input from the in-vehicle sensor, optical sensor, intake sensor and ambient sensor, and potentio tem-
perature control (PTC).
When the air flow is increased, the blower motor speed is adjusted gradually to prevent a sudden increase in
air flow.
In addition to manual air flow control and the usual automatic air flow control, starting air flow control, low
water temperature starting control and high passenger compartment temperature starting control are avail-
able.
Starting Blower Speed Control
Start up from cold soak condition (Automatic mode).
In a cold start up condition where the engine coolant temperature is below 50°C (122°F), the blower will not
operate at blower speed 1 for a short period of time (up to 210 seconds). The exact start delay time varies
depending on the ambient and engine coolant temperatures.
In the most extreme case (very low ambient temperature) the blower starting delay will be 210 seconds as
described above. After the coolant temperature reaches 50°C (122°F), or the 210 seconds has elapsed, the
blower speed will increase to the objective blower speed.
Start up from usual operating or hot soak condition (Automatic mode).
The blower will begin operation momentarily after the AUTO switch is pushed. The blower speed will gradually
rise to the objective speed over a time period of 3 seconds or less (actual time depends on the objective
blower speed).
WJIA1357E

TROUBLE DIAGNOSIS
ATC-95
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Revision: October 20052005 QX56
Blower Speed Compensation - Sunload
When the in-vehicle temperature and the set temperature are very close, the blower will be operating at low
speed. The speed will vary depending on the sunload. During conditions of low or no sunload, the blower
operates at low speed. During high sunload conditions, the front air control causes the blower speed to
increase.
Blower Speed Control Specification
COMPONENT DESCRIPTION
Variable Blower Control
The variable blower control is located on the cooling unit. The vari-
able blower control receives a gate voltage from the front air control
to steplessly maintain the blower motor voltage in the 0 to 5 volt
range (approx.).
DIAGNOSTIC PROCEDURE FOR BLOWER MOTOR
SYMPTOM: Blower motor operation is malfunctioning under starting
blower speed control.
WJIA0441E
WJIA0559E
WJIA1358E