2006 INFINITI QX56 ignition

ATC-118
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
6. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector and front air control connector.
3. Check continuity between BCM harness connector M18 terminal 27 and front air control harness connector M49 terminal 12.
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.
7. CHECK VOLTAGE FOR FRONT AIR CONTROL (COMPRESSOR ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49 terminal 12 and ground.
OK or NG
OK >> GO TO 8.
NG-1 >> If the voltage is approx. 5V when A/C switch is ON, replace front air control. Refer to ATC-144,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when A/C switch is OFF, replace BCM. Refer to BCS-20, "
BCM" .
8. CHECK REFRIGERANT PRESSURE SENSOR
WITH CONSULT-II
1. Start engine.
2. Check voltage of refrigerant pressure sensor. Refer to AT C - 3 4 , "
CONSULT-II Function (HVAC)" .
WITHOUT CONSULT-II
1. Start engine.
2. Check voltage between ECM harness connector F54 terminal 70 and ground.
OK or NG
OK >>
WITH CONSULT-II
GO TO 9.

WITHOUT CONSULT-II
GO TO 10.
NG >> Refer to EC-630, "
REFRIGERANT PRESSURE SENSOR" .
27 - 12 Continuity should exist.
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Terminals
Condition Voltage
(+)
(-)
Front air
control con-
nector Terminal No.
M49 12 Ground A/C switch: ON Approx. 0V
A/C switch: OFF Approx. 5V
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Te r m i n a l s
ConditionVoltage
(+)
(-)
ECM con-
nector Terminal No.
F54 70 Ground A/C switch: ON Approx. 0.36 - 3.88V
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Revision: November 2009 2006 QX56
9. CHECK BCM INPUT (FAN ON) SIGNAL
Check FAN ON/OFF signal. Refer to AT C - 3 4 , "
CONSULT-II Function
(HVAC)" .
OK or NG
OK >> GO TO 12.
NG >> GO TO 10.
10. CHECK CIRCUIT CONTINUITY BETWEEN BCM AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect BCM connector and front air control connector.
3. Check continuity between BCM harness connector M18 terminal 28 and front air control harness connector M49 terminal 10.
OK or NG
OK >> GO TO 11.
NG >> Repair harness or connector.
11 . CHECK VOLTAGE FOR FRONT AIR CONTROL (FAN ON SIGNAL)
1. Reconnect BCM connector and front air control connector.
2. Turn ignition switch ON.
3. Check voltage between front air control harness connector M49 terminal 10 and ground.
OK or NG
OK >> GO TO 12.
NG-1 >> If the voltage is approx. 5V when blower motor is ON, replace front air control. Refer to ATC-144,
"FRONT AIR CONTROL" .
NG-2 >> If the voltage is approx. 0V when blower motor is OFF, replace BCM. Refer to BCS-20, "
BCM" .
FRONT BLOWER CONTROL
DIAL ON
: FAN ON SIG ON
FRONT BLOWER CONTROL
DIAL OFF : FAN ON SIG OFF
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28 - 10
Continuity should exist.
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Terminals
Condition Voltage
(+)
(-)
Front air con-
trol connector Terminal No.
M49 10GroundA/C switch: ON
Blower motor
operates
Approx. 0V
A/C switch: OFF Approx. 5V
WJIA0451E

ATC-132
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Water Valve CircuitEJS003Y1
COMPONENT DESCRIPTION
Water Valve
The water valve (1) cuts the flow of engine coolant to the front and
rear heater cores to allow for maximum cooling during A/C opera-
tion. It is controlled by the front air control.
DIAGNOSTIC PROCEDURE FOR WATER VALVE
1. CHECK WATER VALVE POWER AND GROUND CIRCUITS
1. Disconnect water valve connector F68.
2. Turn ignition switch ON.
3. Rotate temperature control dial (driver) to 32 °C (90 °F).
4. Check voltage between water valve harness connector F68 ter- minal 1 and terminal 2 while rotating temperature control dial
(driver) to 16 °C (60 °F).
OK or NG
OK >> GO TO 3.
NG >> GO TO 2.
2. CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 1 and front air control harness connector M50 (B)
terminal 29.
4. Check continuity between water valve harness connector F68 (A) terminal 1 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL" .
NG >> Repair harness or connector.
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Connector Te r m i n a l s
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 1 2Rotate temperature
control dial Battery
voltage
WJIA1792E
1 - 29 : Continuity should exist.
1 - Ground : Continuity should not exist.
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3. CHECK WATER VALVE POWER AND GROUND CIRCUITS
1. Rotate temperature control dial (driver) to 16 °C (60 °F).
2. Check voltage between water valve harness connector F68 ter- minal 1 and terminal 2 while rotating temperature control dial
(driver) to 32 °C (90 °F).
OK or NG
OK >> Replace the water valve.
NG >> GO TO 4.
4. CHECK WATER VALVE CONTROL OUTPUT CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front air control connector M50.
3. Check continuity between water valve harness connector F68 (A) terminal 2 and front air control harness connector M50 (B)
terminal 30.
4. Check continuity between water valve harness connector F68 (A) terminal 2 and ground.
OK or NG
OK >> Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL" .
NG >> Repair harness or connector.
Connector Terminals
Condition Voltage
(Approx.)
(+) (-)
Water valve: F68 2 1Rotate temperature
control dial Battery
voltage
WJIA1794E
2 - 30 : Continuity should exist.
2 - Ground : Continuity should not exist.
WJIA1796E

ATC-134
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
Ambient Sensor CircuitEJS003Y2
COMPONENT DESCRIPTION
Ambient Sensor
The ambient sensor is attached on the radiator core support (left
side). It detects ambient temperature and converts it into a value
which is then input into the front air control.
AMBIENT TEMPERATURE INPUT PROCESS
The front air control includes a processing circuit for the ambient sensor input. However, when the tempera-
ture detected by the ambient sensor increases quickly, the processing circuit retards the front air control func-
tion. It only allows the front air control to recognize an ambient temperature increase of 0.33°C (0.6 °F) per 100
seconds.
This prevents constant adjustments due to momentary conditions, such as stopping after high speed driving.
Although the actual ambient temperature has not changed, the temperature detected by the ambient sensor
will increase. This is because the heat from the engine compartment can radiate to the front grille area, loca-
tion of the ambient sensor.
DIAGNOSTIC PROCEDURE FOR AMBIENT SENSOR
SYMPTOM: Ambient sensor circuit is open or shorted. Using the
CONSULT-II, DTC B257B or B257C is displayed. Without a CON-
SULT-II, code 40 or 41 is indicated on front air control as a result of
conducting the front air control self-diagnosis.
1. CHECK VOLTAGE BETWEEN AMBIENT SENSOR AND GROUND
1. Disconnect ambient sensor connector.
2. Turn ignition switch ON.
3. Check voltage between ambient sensor harness connector E1 terminal 1 and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
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1 - Ground : Approx. 5V
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Revision: November 2009 2006 QX56
2. CHECK CIRCUIT CONTINUITY BETWEEN AMBIENT SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between ambient sensor harness connector E1 terminal 1 and front air control harness connector M49 termi-
nal 17.
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
3. CHECK AMBIENT SENSOR
Refer to ATC-134, "
Ambient Sensor Circuit" .
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL"
2. Go to AT C - 5 6 , "A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> 1. Replace ambient sensor. Refer to ATC-145, "
AMBIENT SENSOR" .
2. Go to AT C - 5 6 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
4. CHECK CIRCUIT CONTINUITY BETWEEN AMBIENT SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between ambient sensor harness connector E1 terminal 2 and front air control harness connector M49 termi-
nal 21.
4. Check continuity between ambient sensor harness connector E1 terminal 2 and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL"
2. Go to self-diagnosis AT C - 5 6 , "A/C System Self-diagnosis Function" and perform self-diagno-
sis.
NG >> Repair harness or connector. 1 - 17
: Continuity should exist.
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2 - 21: Continuity should exist.
2 - Ground : Continuity should not exist.
WJIA0565E

ATC-138
TROUBLE DIAGNOSIS
Revision: November 20092006 QX56
DIAGNOSTIC PROCEDURE FOR IN-VEHICLE SENSOR
SYMPTOM: In-vehicle sensor circuit is open or shorted. Using the
CONSULT-II, DTC B2578 or B2579 is displayed. Without a CON-
SULT-II code 30, 31, 44 or 46 is indicated on front air control as a
result of conducting self-diagnosis.
1. CHECK IN-VEHICLE SENSOR CIRCUIT
Self-diagnosis DTC B2578 or B2579 (with CONSULT-II) or code 30, 31 44 or 46 (without CONSULT-II) is
present?
YES or NO
YES >> GO TO 6.
NO >> GO TO 2.
2. CHECK VOLTAGE BETWEEN IN-VEHICLE SENSOR AND GROUND
1. Disconnect in-vehicle sensor connector.
2. Turn ignition switch ON.
3. Check voltage between in-vehicle sensor harness connector M32 terminal 4 and ground.
OK or NG
OK >> GO TO 3.
NG >> GO TO 5.
3. CHECK CIRCUIT CONTINUITY BETWEEN IN-VEHICLE SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector M49.
3. Check continuity between in-vehicle sensor harness connector M32 terminal 1 and front air control harness connector M49 ter-
minal 21.
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4. CHECK IN-VEHICLE SENSOR
Refer to ATC-142, "
Intake Sensor Circuit" .
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL" .
2. Go to AT C - 5 6 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> 1. Replace in-vehicle sensor. Refer to ATC-146, "
IN-VEHICLE SENSOR" .
2. Go to AT C - 5 6 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
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4 - Ground : Approx. 5V.
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1 - 21 : Continuity should exist.
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Revision: November 2009 2006 QX56
5. CHECK CIRCUIT CONTINUITY BETWEEN IN-VEHICLE SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between in-vehicle sensor harness connector M32 terminal 4 and front air control harness connector M50 ter-
minal 32.
4. Check continuity between in-vehicle sensor harness connector M32 terminal 4 and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL" .
2. Go to AT C - 5 6 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> Repair harness or connector.
6. CHECK CIRCUIT CONTINUITY BETWEEN IN-VEHICLE SENSOR MOTOR AND FRONT AIR CON-
TROL (SELF-DIAGNOSIS CODES 30, 31, 44, 46 OR DTC B2578, B2579)
1. Turn ignition switch OFF.
2. Disconnect front air control connector and in-vehicle sensor con- nector.
3. Check continuity between in-vehicle sensor harness connector M32 terminal 2 and 3 and front air control harness connector
M50 terminal 44 and 43.
4. Check continuity between in-vehicle sensor harness connector M32 terminal 2 and 3 and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-144, "FRONT AIR CONTROL" .
2. Go to AT C - 5 6 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> Repair harness or connector. 4 - 32
: Continuity should exist.
4 - Ground Continuity should not exist.
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2 - 44: Continuity should exist.
3 - 43 : Continuity should exist.
2, 3 - Ground :Continuity should not exist.
LJIA0093E