2005 INFINITI QX4 ignition

TROUBLE DIAGNOSIS
ATC-135
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AT C
Revision: October 20052005 QX56
4. CHECK WATER VALVE RELAY
Check water valve relay. Refer to ATC-136, "
Wat er Va lve Relay" .
OK or NG
OK >> GO TO 5
NG >> Replace water valve relay.
5. CHECK WATER VALVE GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect water valve connector F68.
3. Check continuity between water valve harness connector F68
terminal - (B) and ground.
OK or NG
OK >> GO TO 6.
NG >> Repair harness or connector.
6. CHECK WATER VALVE POWER CIRCUIT
1. Check continuity between water valve relay connector terminal 5
(Y/L) and water valve connector F68 terminal + (Y/L)
2. Check continuity between water valve relay harness connector
M7 terminal 5 (Y/L) and ground.
OK or NG
OK >> Replace water valve.
NG >> Repair harness or connector.(-) - Ground : Continuity should exist.
WJIA1373E
5 - + : Continuity should exist.
5 - Ground : Continuity should not exist.
WJIA0903E

TROUBLE DIAGNOSIS
ATC-137
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AT C
Revision: October 20052005 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 (P) 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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ATC-138
TROUBLE DIAGNOSIS
Revision: October 20052005 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 (P) and front air control harness connector M49
terminal 17 (P).
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
3. CHECK AMBIENT SENSOR
Refer to ATC-137, "
Ambient Sensor Circuit" .
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL"
2. Go to self-diagnosis AT C - 5 5 , "A/C System Self-diagnosis Function" and perform self-diagno-
sis.
NG >> 1. Replace ambient sensor.
2. Go to self-diagnosis AT C - 5 5 , "
A/C System Self-diagnosis Function" and perform self-diagno-
sis.
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 (V/R) and front air control harness connector M49
terminal 21 (V/R).
4. Check continuity between ambient sensor harness connector
E1 terminal 2 (V/R) and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL"
2. Go to self-diagnosis AT C - 5 5 , "A/C System Self-diagnosis Function" and perform self-diagno-
sis.
NG >> Repair harness or connector.1 - 17 : Continuity should exist.
WJIA0564E
2 - 21 : Continuity should exist.
2 - Ground : Continuity should not exist.
WJIA0565E

TROUBLE DIAGNOSIS
ATC-141
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AT C
Revision: October 20052005 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 or 31 is indicated on front air control as a result of
conducting the front air control self-diagnosis.
1. CHECK IN-VEHICLE SENSOR CIRCUIT
Are diagnostic codes 30, 31 or DTC B2578, B2579 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 (LG/R) 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 (V/R) and front air control harness connector
M49 terminal 21 (V/R).
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4. CHECK IN-VEHICLE SENSOR
Refer to ATC-145, "
Intake Sensor Circuit" .
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL" .
2. Go to AT C - 5 5 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> 1. Replace in-vehicle sensor. Refer to ATC-149, "
IN-VEHICLE SENSOR" .
2. Go to AT C - 5 5 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
WJIA0460E
4 - Ground : Approx. 5V.
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1 - 21 : Continuity should exist.
LJIA0090E

ATC-142
TROUBLE DIAGNOSIS
Revision: October 20052005 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 (LG/R) and front air control harness connector
M50 terminal 32 (LG/R).
4. Check continuity between in-vehicle sensor harness connector
M32 terminal 4 (LG/R) and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL" .
2. Go to self-diagnosis AT C - 5 5 , "
A/C System Self-diagnosis Function" and perform self-diagno-
sis.
NG >> Repair harness or connector.
6. CHECK CIRCUIT CONTINUITY BETWEEN IN-VEHICLE SENSOR MOTOR AND FRONT AIR CON-
TROL (SELF-DIAGNOSIS CODES 44, 46 OR DTC B2578, 2579)
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 (O/B) and 3 (BR/Y) and front air control harness
connector M50 terminal 44 (O/B) and 43 (BR/Y).
4. Check continuity between in-vehicle sensor harness connector
M32 terminal 2 (O/B) and 3 (BR/Y) and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL" .
2. Go to ATC-55, "
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.
LJIA0091E
2 - 44 : Continuity should exist.
3 - 43 : Continuity should exist.
2, 3 - Ground :Continuity should not exist.
LJIA0093E

ATC-144
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
DIAGNOSTIC PROCEDURE FOR OPTICAL SENSOR
SYMPTOM: Optical sensor circuit is open or shorted. Using the
CONSULT-II, DTC B257F or B2580 is displayed. Without a CON-
SULT-II, code 50 or 51 is indicated on front air control as a result of
conducting the front air control self-diagnosis.
1. CHECK CIRCUIT CONTINUITY BETWEEN OPTICAL SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector and optical sensor con-
nector.
3. Check continuity between optical sensor harness connector
M402 terminal 1 (W/V) and 2 (G/O) and front air control harness
connector M50 terminal 31 (W/V) and 40 (G/O).
4. Check continuity between optical sensor harness connector
M402 terminal 1 (W/V) and 2 (G/O) and ground.
OK or NG
OK >> GO TO 2.
NG >> Repair harness or connector.
2. CHECK CIRCUIT CONTINUITY BETWEEN OPTICAL SENSOR AND BCM
1. Turn ignition switch OFF.
2. Disconnect BCM connector and optical sensor connector.
3. Check continuity between optical sensor harness connector
M402 terminal 3 (P) and BCM harness connector M18 terminal
18 (P).
4. Check continuity between optical sensor harness connector
M402 terminal 3 (P) and ground.
OK or NG
OK >> Replace optical sensor. Refer to ATC-150, "OPTICAL SENSOR" .
NG >> Repair harness or connector.
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1 - 31 : Continuity should exist.
2 - 40 : Continuity should exist.
1, 2 - Ground. : Continuity should not exist.
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3 - 18 : Continuity should exist.
3 - Ground : Continuity should not exist.
WJIA1446E

TROUBLE DIAGNOSIS
ATC-145
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Revision: October 20052005 QX56
Intake Sensor CircuitEJS003Y5
COMPONENT DESCRIPTION
Intake Sensor
The intake sensor is located on the heater & cooling unit. It converts
temperature of air after it passes through the evaporator into a value
which is then input to the front air control.
DIAGNOSTIC PROCEDURE FOR INTAKE SENSOR
SYMPTOM: Intake sensor circuit is open or shorted. Using the CON-
SULT-II, DTC B2581 or B2582 is displayed. Without a CONSULT-II,
code 56 or 57 is indicated on front air control as a result of conduct-
ing the front air control self-diagnosis.
1. CHECK VOLTAGE BETWEEN INTAKE SENSOR AND GROUND
1. Disconnect intake sensor connector.
2. Turn ignition switch ON.
3. Check voltage between intake sensor harness connector M146
terminal 2 (L/B) and ground.
OK or NG
OK >> GO TO 2.
NG >> GO TO 4.
2. CHECK CIRCUIT CONTINUITY BETWEEN INTAKE SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between intake sensor harness connector
M146 terminal 1 (V/R) and front air control harness connector
M49 terminal 21 (V/R).
OK or NG
OK >> GO TO 3.
NG >> Repair harness or connector.
WJIA0571E
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2 - Ground : Approx. 5V
WJIA1375E
1 - 21 : Continuity should exist.
WJIA1376E

ATC-146
TROUBLE DIAGNOSIS
Revision: October 20052005 QX56
3. CHECK INTAKE SENSOR
Refer to ATC-146, "
Intake Sensor" .
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL"
2. Go to self-diagnosisAT C - 5 5 , "A/C System Self-diagnosis Function" and perform self-diagnosis.
NG >> 1. Replace intake sensor. Refer to ATC-151, "
INTAKE SENSOR" .
2. Go to self-diagnosisAT C - 5 5 , "
A/C System Self-diagnosis Function" and perform self-diagnosis.
4. CHECK CIRCUIT CONTINUITY BETWEEN INTAKE SENSOR AND FRONT AIR CONTROL
1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between intake sensor harness connector
M146 terminal 2 (L/B) and front air control harness connector
M49 terminal 9 (L/B).
4. Check continuity between intake sensor harness connector
M146 terminal 2 (L/B) and ground.
OK or NG
OK >> 1. Replace front air control. Refer to ATC-147, "FRONT AIR CONTROL" .
2. Go to self-diagnosis AT C - 5 5 , "
A/C System Self-diagnosis Function" and perform self-diagno-
sis.
NG >> Repair harness or connector.
COMPONENT INSPECTION
Intake Sensor
After disconnecting intake sensor connector, measure resistance
between terminals 1 and 2 at sensor harness side, using the table
below.
If NG, replace intake sensor.2 - 9 : Continuity should exist.
2 - Ground : Continuity should not exist.
WJIA1377E
Temperature °C (°F) Resistance kΩ
−15 (5) 209.0
−10 (14) 160.0
−5 (23) 123.0
0 (32) 95.8
5 (41) 74.9
10 (50) 58.9
15 (59) 46.7
20 (68) 37.3
25 (77) 30.0
30 (86) 24.2
35 (95) 19.7
40 (104) 16.1
45 (113) 13.2
WJIA1378E