INFINITI QX4 2005 Factory Service Manual

ATC-56
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
SELF-DIAGNOSIS CODE CHART
Code No. Reference page
02 EE changed by calibrationATC-147, "
FRONT AIR CONTROL"
03 Battery voltage out of rangeSC-4, "BATTERY"
12 Air mix door motor (Passenger) circuit failureAT C - 7 6 , "DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR
MOTOR (PASSENGER)"
20 BCM not responding to A/C requestAT C - 11 6 , "DIAGNOSTIC PROCEDURE FOR MAGNET
CLUTCH"
21 BCM not responding to rear defroster requestGW-77, "REAR WINDOW DEFOGGER"
22 Air mix door motor (Driver) circuit failureAT C - 7 2 , "DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR
MOTOR (DRIVER)"
30 In-vehicle sensor circuit out of range (low)
ATC-145, "Intake Sensor Circuit"31 In-vehicle sensor circuit out of range (high)
38 Air mix door motor (rear) circuit failureAT C - 7 9 , "
DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR
MOTOR (REAR)"
40 Ambient sensor circuit short
ATC-137, "Ambient Sensor Circuit"41 Ambient sensor circuit open
44 In-vehicle sensor motor circuit open
ATC-145, "
Intake Sensor Circuit"46 In-vehicle sensor motor circuit short
50 Optical sensor (Driver) circuit open or short
ATC-143, "
Optical Sensor Circuit"52 Optical sensor (Passenger) circuit open or short
56 Intake sensor circuit short
ATC-145, "
Intake Sensor Circuit"57 Intake sensor circuit open
62 Defroster door motor circuit failureAT C - 8 7 , "
Defroster Door Motor Circuit"
80 CAN bus faultLAN-5, "CAN COMMUNICATION"
82 Intake door motor (driver) circuit malfunctionAT C - 8 5 , "DIAGNOSTIC PROCEDURE FOR INTAKE DOOR
MOTOR"
90 Stuck buttonATC-147, "FRONT AIR CONTROL"
92 Mode door motor circuit failureAT C - 6 4 , "Mode Door Motor Circuit"

TROUBLE DIAGNOSIS
ATC-57
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B
AT C
Revision: October 20052005 QX56
Operational Check (Front)EJS003XL
The purpose of the operational check is to confirm that the system operates properly.
CHECKING MEMORY FUNCTION
1. Set the temperature to 90°F or 32°C.
2. Turn front blower control dial counterclockwise until system
shuts OFF.
3. Turn ignition switch OFF.
4. Turn ignition switch ON.
5. Press the AUTO switch.
6. Confirm that the set temperature remains at previous tempera-
ture.
7. Turn front blower control counterclockwise until system shuts
OFF.
If NG, go to trouble diagnosis procedure for ATC-133, "
Memory
Function" .
If OK, continue with next check.
CHECKING BLOWER
1. Press the AUTO switch. Blower should operate on low speed.
The blower symbol should have one blade lit (on display).
2. Turn the front blower control dial again, and continue checking
blower speed and blower symbol until all speeds are checked.
3. Leave blower on MAX speed.
If NG, go to trouble diagnosis procedure for AT C - 9 5 , "
DIAGNOSTIC
PROCEDURE FOR BLOWER MOTOR"ATC-95, "DIAGNOSTIC
PROCEDURE FOR BLOWER MOTOR" .
If OK, continue with next check.Conditions : Engine running and at normal operating temperature
WJIA1040E
WJIA1043E
WJIA1040E
WJIA1068E

ATC-58
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
CHECKING DISCHARGE AIR
1. Press MODE switch four times and the DEF switch.
2. Each position indicator should change shape (on display).
3. Confirm that discharge air comes out according to the air distri-
bution table. Refer to ATC-29, "
Discharge Air Flow" .
Mode door position is checked in the next step.
If NG, go to trouble diagnosis procedure for AT C - 6 4 , "
Mode Door
Motor Circuit" .
If OK, continue the check.
NOTE:
Confirm that the compressor clutch is engaged (sound or visual
inspection) and intake door position is at fresh when the DEF or D/F
is selected.
CHECKING RECIRCULATION
1. Press recirculation ( ) switch one time. Recirculation indica-
tor should illuminate.
2. Press recirculation ( ) switch one more time. Recirculation
indicator should go off.
3. Listen for intake door position change (blower sound should
change slightly).
If NG, go to trouble diagnosis procedure for ATC-83, "
Intake Door
Motor Circuit" .
If OK, continue the check.
NOTE:
Confirm that the compressor clutch is engaged (sound or visual
inspection) and intake door position is at fresh when the DEF or D/F is selected.
CHECKING TEMPERATURE DECREASE
1. Rotate temperature control dial (driver side or passenger side)
counterclockwise until 16°C (60°F) is displayed.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-121, "
Insufficient Cooling" . If
air mix door motor appears to be malfunctioning, go to ATC-72,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(DRIVER)" or AT C - 7 6 , "DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER)" .
If OK, continue the check.
WJIA1045E
WJIA0528E
WJIA1046E
WJIA1047E

TROUBLE DIAGNOSIS
ATC-59
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AT C
Revision: October 20052005 QX56
CHECKING TEMPERATURE INCREASE
1. Rotate temperature control dial clockwise (driver side or passen-
ger side) until 32°C (90°F) is displayed.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-128, "
Insufficient Heating" . If
air mix door motor appears to be malfunctioning, go to AT C - 7 2 ,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(DRIVER)" or AT C - 7 6 , "DIAGNOSTIC PROCEDURE FOR AIR MIX
DOOR MOTOR (PASSENGER)" .
If OK, continue with next check.
CHECK A/C SWITCH
1. Press A/C switch when AUTO switch is ON, or in manual mode.
2. A/C switch indicator will turn ON.

Confirm that the compressor clutch engages (sound or visual
inspection).
If NG, go to trouble diagnosis procedure for AT C - 11 5
.
If OK, continue with next check.
CHECKING AUTO MODE
1. Press AUTO switch.
2. Display should indicate AUTO.

If ambient temperature is warm, and selected temperature is
cool, confirm that the compressor clutch engages (sound or
visual inspection). (Discharge air and blower speed will
depend on ambient, in-vehicle, and set temperatures.)
If NG, go to trouble diagnosis procedure for ATC-61, "
Power Supply
and Ground Circuit for Front Air Control" , then if necessary, trouble
diagnosis procedure for ATC-115, "
Magnet Clutch Circuit" .
If all operational checks are OK (symptom cannot be duplicated), go
to malfunction Simulation Tests in ATC-38, "
How to Perform Trouble
Diagnosis for Quick and Accurate Repair" and perform tests as out-
lined to simulate driving conditions environment. If symptom appears. Refer to AT C - 3 8 , "
How to Perform Trou-
ble Diagnosis for Quick and Accurate Repair" , ATC-38, "SYMPTOM TABLE" and perform applicable trouble
diagnosis procedures.
WJIA1048E
WJIA1049E
WJIA1043E

ATC-60
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
Operational Check (Rear)EJS003XM
The purpose of the operational check is to confirm that the system operates properly.
CHECKING BLOWER
1. Turn the rear blower control dial to switch position "1". Blower
should operate on low speed.
2. Turn the rear blower control dial counterclockwise to switch
position "2", "3", and "4" until all speeds are checked.
3. Leave blower on MAX speed.
If NG, go to trouble diagnosis procedure for ATC-101, "
Rear Blower
Motor Circuit" .
If OK, continue the check.
CHECKING TEMPERATURE DECREASE
1. Rotate temperature and mode dial fully counterclockwise.
2. Check for cold air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation if OK, go to
trouble diagnosis procedure for ATC-121, "
Insufficient Cooling" . If
air mix door motor appears to be malfunctioning, go to ATC-79,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(REAR)" .
If OK, continue the check.
CHECKING TEMPERATURE INCREASE
1. Rotate temperature and mode dial clockwise.
2. Check for hot air at appropriate discharge air outlets.
If NG, listen for sound of air mix door motor operation. If OK, go to
trouble diagnosis procedure for ATC-128, "
Insufficient Heating" . If
air mix door motor appears to be malfunctioning, go to ATC-79,
"DIAGNOSTIC PROCEDURE FOR AIR MIX DOOR MOTOR
(REAR)" .
If OK, continue the check.Conditions : Engine running and at normal operating temperature
WJIA1350E
WJIA1069E
WJIA1070E

TROUBLE DIAGNOSIS
ATC-61
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B
AT C
Revision: October 20052005 QX56
Power Supply and Ground Circuit for Front Air ControlEJS003XN
SYMPTOM: A/C system does not come on.
INSPECTION FLOW
*1ATC-61, "Power Supply and Ground
Circuit for Front Air Control"
*2AT C - 5 7 , "Operational Check (Front)"
or AT C - 6 0 , "
Operational Check
(Rear)"
WJIA1439E

ATC-62
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
COMPONENT DESCRIPTION
Front Air Control
The front air control has a built-in microcomputer which processes
information sent from various sensors needed for air conditioner
operation. The air mix door motors, mode door motor, intake door
motor, defroster door motor, blower motor and compressor are then
controlled.
The front air control is unitized with control mechanisms. When the
various switches and temperature dials are operated, data is input to
the front air control.
Self-diagnostic functions are also built into the front air control to pro-
vide quick check of malfunctions in the auto air conditioner system.
Potentio Temperature Control (PTC)
There are two PTCs (passenger and driver) built into the front air
control. They can be set at an interval of 0.5°C (1.0°F) in the 16°C
(60°F) to 32°C (90°F) temperature range by rotating the temperature
dial. The set temperature is displayed.
DIAGNOSTIC PROCEDURE FOR A/C SYSTEM
SYMPTOM: A/C system does not come on.
WJIA0544E
WJIA1050E
WJIA0414E

TROUBLE DIAGNOSIS
ATC-63
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AT C
Revision: October 20052005 QX56
1. CHECK POWER SUPPLY CIRCUITS FOR FRONT AIR CONTROL
1. Disconnect front air control connector.
2. Check voltage between front air control harness connector M49
terminals 14 (Y/G) and 22 (Y/R), and ground.
OK or NG
OK >> GO TO 2.
NG >> Check 10A fuses [Nos. 8 and 19, located in the fuse block (J/B)]. Refer to PG-76, "
FUSE BLOCK-
JUNCTION BOX(J/B)" .

If fuses are OK, check harness for open circuit. Repair or replace as necessary.

If fuses are NG, replace fuse and check harness for short circuit. Repair or replace as neces-
sary.
2. CHECK GROUND CIRCUIT FOR FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Check continuity between front air control harness connector
M49 terminal 1 (B) and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-147, "FRONT
AIR CONTROL" .
NG >> Repair harness or connector.
Terminals Ignition switch position
(+)
(-) OFF ACC ON Front air
control
connectorTe r m i n a l N o .
(Wire color)
M49 14 (Y/G)
GroundApprox. 0V Approx. 0VBattery
voltage
M49 22 (Y/R)Battery
voltageBattery
voltageBattery
voltage
WJIA0415E
1 - Ground : Continuity should exist.
WJIA1351E

ATC-64
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
Mode Door Motor CircuitEJS003XO
SYMPTOM:

Air outlet does not change.

Mode door motor does not operate normally.
INSPECTION FLOW
*1AT C - 2 9 , "Discharge Air Flow"*2AT C - 5 7 , "Operational Check
(Front)"
*3AT C - 5 5 , "A/C System Self-diagnosis
Function"
*4AT C - 5 6 , "SELF-DIAGNOSIS CODE
CHART"
*5AT C - 6 6 , "DIAGNOSTIC PROCE-
DURE FOR MODE DOOR
MOTOR"
*6ATC-147, "FRONT AIR CONTROL"
WJIA1937E

TROUBLE DIAGNOSIS
ATC-65
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B
AT C
Revision: October 20052005 QX56
SYSTEM DESCRIPTION
Component Parts
Mode door control system components are:

Front air control

Mode door motor

PBR (built into mode door motor)

In-vehicle sensor

Ambient sensor

Optical sensor

Intake sensor
System Operation
The mode door position (vent, B/L, foot, and defrost) is set by the front air control by means of the mode door
motor. When a mode door position is selected on the front air control, voltage is applied to one circuit of the
mode door motor while ground is applied to the other circuit, causing the mode door motor to rotate. The direc-
tion of rotation is determined by which circuit has voltage applied to it, and which one has ground applied to it.
The front air control monitors the mode door position by measuring the voltage signal on the PBR circuit.
In AUTO mode the mode door position is set by the front air control which determines the proper position
based on inputs from the in-vehicle sensor, ambient sensor, optical sensor, intake sensor, and the temperature
selected by the driver or passenger.
Mode Door Control Specification
WJIA1240E
WJIA0434E