INFINITI QX56 2007 Factory Service Manual

TROUBLE DIAGNOSISATC-81
< SERVICE INFORMATION >
C
DE
F
G H
I
K L
M A
B
AT C
N
O P
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.
1.CHECK FUSES
Check 20A fuses [No. 24 and 27 (Located in the fuse and fusible link box)]. For fuse layout. Refer to PG-
74PG-74.
OK or NG
OK >> GO TO 2.
NG >> GO TO 10.
2.CHECK FRONT BLOWER MOTOR POWER SUPPLY CIRCUIT
WJIA0559E
WJIA1358E
Fuses are good.

ATC-82
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Disconnect front blower motor connector.
3. Turn ignition switch ON.
4. Press the mode switch to select any mode except OFF.
5. Turn the front blower control dial to high.
6. Check voltage between front blower motor harness connector M62 terminal 2 and ground.
OK or NG
OK >> GO TO 12.
NG >> GO TO 3.
3.CHECK FRONT BLOWER MOTOR RELAY (S WITCH SIDE) POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front blower motor relay.
3. Check voltage between front blower motor relay harness con- nector M107 terminal 5 and ground.
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4.CHECK FRONT BLOWER MOTOR RELAY
Turn ignition switch OFF.
Refer to "Front Blower Motor Relay" .
OK or NG
OK >> GO TO 5.
NG >> Replace front blower motor relay.
5.CHECK FRONT BLOWER MOTOR RELA Y (SWITCH SIDE) CIRCUIT FOR OPEN
Check continuity between front blower motor relay harness connec-
tor M107 terminal 3 and front blower motor harness connector M62
terminal 2.
OK or NG
OK >> GO TO 6.
NG >> Repair harness or connector.
6.CHECK VARIABLE BLOWER CONTROL POWER SUPPLY CIRCUIT FOR OPEN
1. Disconnect variable blower control harness connector.
2. Check continuity between front blower motor relay harness con- nector M107 terminals 3 and variable blower control harness
connector M122 terminal 1.
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector. 2 - Ground : Battery voltage.
WJIA1331E
5 - Ground : Battery voltage.
WJIA1886E
3 - 2 : Continuity should exist.
WJIA1360E
3 - 1 : Continuity should exist.
WJIA1361E

TROUBLE DIAGNOSISATC-83
< SERVICE INFORMATION >
C
DE
F
G H
I
K L
M A
B
AT C
N
O P
7.CHECK VARIABLE BLOWER CONTROL SIGNAL CIRCUIT
1. Disconnect front air control connector.
2. Check continuity between front air control harness connector
M49 terminal 13 and variable blower control harness connector
M122 terminal 2.
OK or NG
OK >> GO TO 8.
NG >> Repair harness or connector.
8.CHECK FRONT BLOWER MOTOR RELAY (COIL SIDE) POWER SUPPLY
1. Turn ignition switch ON.
2. Check voltage between front blower motor relay harness con- nector M107 terminal 2 and ground.
OK or NG
OK >> GO TO 9.
NG >> Repair harness or connector.
9.CHECK FRONT BLOWER MOTOR RELAY (COIL SIDE) GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Check continuity between front blower motor relay connector M107 terminal 1 and front air control harness connector M49 ter-
minal 26.
OK or NG
OK >> Replace front air control. Refer to ATC-123, "Removal
and Installation" .
NG >> Repair harness or connector.
10.REPLACE FUSES
1. Replace fuses.
2. Activate the front blower motor.
3. Do fuses blow?
YES or NO
YES >> GO TO 11.
NO >> Inspection End.
11 .CHECK FRONT BLOWER MOTOR POWER SUPPLY CIRCUIT FOR SHORT 13 - 2 : Continuity should exist.
WJIA1362E
2 - Ground : Battery voltage.
WJIA1363E
1 - 26 : Continuity should exist.
WJIA1364E

ATC-84
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Disconnect front blower motor connector and variable blowercontrol connector.
3. Check continuity between variable blower control harness con-
nector M122 terminal 1 and ground.
OK or NG
OK >> GO TO 12.
NG >> Repair harness or connector.
12.CHECK VARIABLE BLOWER CONTROL SIGNAL CIRCUIT
1. Disconnect front air control connector.
2. Check continuity between front air control harness connector M49 terminal 13 and variable blower control harness connector
M122 terminal 2.
OK or NG
OK >> GO TO 13.
NG >> Repair harness or connector.
13.CHECK FRONT BLOWER MOTOR
Refer to "Front Blower Motor" .
OK or NG
OK >> GO TO 14.
NG >> Replace front blower motor. Refer to ATC-123, "
Removal and Installation"
14.CHECK BLOWER MOTOR GROUND CIRCUIT
Check continuity between front blower motor harness connector
M62 terminal 1 and variable blower control harness connector M122
terminal 3.
OK or NG
OK >> GO TO 15.
NG >> Repair harness or connector.
15.CHECK VARIABLE BLOWER CONTROL GROUND CIRCUIT
Check continuity between variable blower control harness connector
M122 terminal 4 and ground.
OK or NG
OK >> Replace variable blower control. Refer to ATC-143.
NG >> Repair harness or connector.
COMPONENT INSPECTION
Front Blower Motor Relay
1 - Ground. : Continuity should not exist.
WJIA1365E
13 - 2 : Continuity should exist.
WJIA1366E
1 - 3 : Continuity should exist.
WJIA1367E
4 - ground : Continuity should exist.
WJIA1368E

TROUBLE DIAGNOSISATC-85
< SERVICE INFORMATION >
C
DE
F
G H
I
K L
M A
B
AT C
N
O P
Check continuity between terminals by supplying 12 volts and
ground to coil side terminals of relay.
Front Blower Motor
Confirm smooth rotation of the blower motor.
• Ensure that there are no foreign particles inside the blower unit.
• Apply 12 volts to terminal 2 and ground to terminal 1 and verify that the motor operates freely and quietly.
Rear Blower Motor CircuitINFOID:0000000003533257
SYMPTOM:
• Blower motor operation is malfunctioning.
INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIO NAL CHECK - REAR AIR CONTROL (FRONT)
1. Press AUTO switch.
2. Set the rear blower control dial (front) to REAR position.
3. Turn the rear blower control dial (rear) and check for rear blower operation. NOTE:
If the engine coolant temperature increases above 111.9 °C (233.6 °F) the front air control turns OFF the
rear blower motor. When the engine coolant temperature drops below 110 °C (230 °F) the front air control
turns the rear blower motor back ON.
4. Continue checking that rear blower speed increases as the rear blower control dial is rotated clockwise.
Does the rear blower motor operate correctly?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK FOR ANY SYMPTOMS
WJIA1401E
WJIA1508E

ATC-86
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Perform a complete operational check for any symptoms. Refer to ATC-50, "Operational Check (Front)".
Does another symptom exist?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair".
NO >> System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 4.
4.CHECK REAR BLOWER CONTROL DIAL (FRONT) CIRCUIT
Check and verify rear blower control dial (front ) operates the rear blower motor in all speeds.
Does blower motor operate in all speeds?
YES >> GO TO 5.
NO >> Refer to ATC-93, "
Rear Air Control Circuit".
5.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis to check for any codes. Refer to ATC-48, "
A/C System Self-Diagnosis Function".
Are any self-diagnosis codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function" .
NO >> GO TO 6.
6.RECHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to ATC-50, "
Operational Check (Front)" .
Does another symptom exist?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" .
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation" .
SYSTEM DESCRIPTION
Component Parts
Rear blower speed control system components are:
• Front air control
• Rear blower switch (front)
• Rear air control
• Rear blower motor resistor
• Rear blower motor
• Rear blower motor relay
System Operation
Rear Blower Control
WJIA1280E

TROUBLE DIAGNOSISATC-87
< SERVICE INFORMATION >
C
DE
F
G H
I
K L
M A
B
AT C
N
O P
When the rear blower control dial (front) is in t he OFF position, the rear blower motor cannot operate.
When the rear blower control dial (front) is in the REAR position, it allows the rear blower switch (rear) to con-
trol the rear blower motor speed. In any other position (1 -4), the rear blower switch (front) controls the rear
blower motor speed regardless of the rear blower switch (rear) position.
DIAGNOSTIC PROCEDURE FOR REAR BLOWER MOTOR
Rear Blower Switch (Rear) Circuit
SYMPTOM:
• Rear blower motor does not rotate when rear blower switch (front) is set to REAR position and the rear
blower switch (rear) is set at 1-4 speed.
1.CHECK REAR BLOWER MOTOR OPERATION
Blower motor rotates normally when rear blower control dial (front) is set at 1 - 4 speed.
OK or NG
OK >> GO TO 2.
NG >> Refer to "Trouble Diagnosis Procedure For Rear Blower Motor (1 - 4 Speed)".
2.CHECK REAR BLOWER SWITCH (FRONT)
Refer to "Rear Blower Switch (Front)".
OK or NG
OK >> GO TO 3.
NG >> Replace rear blower switch (front). Refer to ATC-123, "
Removal and Installation" .
3.CHECK REAR AIR CONTROL
Refer to "Rear Blower Switch (Rear) Circuit".
OK or NG
OK >> GO TO 4.
NG >> Replace rear blower switch (rear). Refer to ATC-123, "
Removal and Installation" .
4.CHECK CIRCUIT CONTINUITY
1. Turn ignition switch OFF.
2. Disconnect rear blower switch (front) connector and rear air con-
trol connector.
3. Check continuity between rear blower switch (front) harness connector M52 terminal 2 and rear blower switch (rear) harness
connector R208 terminal 10.
OK or NG
OK >> Inspection End.
NG >> Repair harness or connector.
Trouble Diagnosis Procedure For Rear Blower Motor (1 - 4 Speed)
SYMPTOM:
• Rear blower motor does not rotate when rear blower control dial (front) is set at 1 - 4 speed.
Inspection Flow
1.CONFIRM SYMPTOM BY PERFORMING OPERAT IONAL CHECK - REAR BLOWER MOTOR
1. Press AUTO switch.
2. Set the rear blower control dial (front) to REAR position.
3. Turn the rear blower control dial (rear) to rear blower speed position 1 and check for rear blower opera- tion.
4. Continue checking that rear blower speed increases as the rear blower control dial is rotated clockwise.
Does the rear blower motor operate correctly?
YES >> GO TO 3.
NO >> GO TO 2.
2.CHECK FOR ANY SYMPTOMS 2 - 10 : Continuity should exist.
WJIA1281E

ATC-88
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Perform a complete operational check for any symptoms. Refer to ATC-50, "Operational Check (Front)".
Does another symptom exist?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair" .
NO >> System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
>> GO TO 4.
4.CHECK REAR BLOWER MOTOR CIRCUIT
Check and verify rear blower motor operates in all speeds.
Does blower motor operate in all speeds?
YES >> GO TO 5.
NO >> Refer to "Trouble Diagnosis Procedure For Rear Blower Motor (1 - 4 Speed)".
5.PERFORM SELF-DIAGNOSIS
Perform self-diagnosis to check for any codes. Refer to ATC-48, "
A/C System Self-Diagnosis Function" .
Are any self-diagnosis codes present?
YES >> Refer to ATC-48, "A/C System Self-Diagnosis Function".
NO >> GO TO 6.
6.RECHECK FOR ANY SYMPTOMS
Perform a complete operational check for any symptoms. Refer to ATC-50, "
Operational Check (Front)" .
Does another symptom exist?
YES >> Refer to ATC-32, "How to Perform Trouble Diagnosis for Quick and Accurate Repair".
NO >> Replace front air control. Refer to ATC-123, "
Removal and Installation".
1.DIAGNOSTIC PROCEDURE
Blower motor rotates normally at each speed.
OK or NG
OK >> Inspection End.
NG >> 1. Does not rotate at any speed, GO TO 2. 2. Does not rotate at 1 - 3 speed, GO TO 13.
3. Does not rotate at 4 speed, GO TO 18.
2.CHECK FUSES
Check 15A fuses [Nos. 10 and 11, located in the fuse block (J/B)]. Refer to PG-73
.
OK or NG
OK >> GO TO 3.
NG >> GO TO 8.
3.CHECK REAR BLOWER MOTOR POWER SUPPLY
1. Turn ignition switch OFF.
2. Disconnect rear blower motor connector.
3. Select any rear blower speed except OFF.
4. Turn ignition switch ON.
5. Check voltage between rear blower motor harness connector B134 terminal 2 and ground.
OK or NG
OK >> GO TO 11.
NG >> GO TO 4. 2 - Ground : Battery voltage.WJIA0596E

TROUBLE DIAGNOSISATC-89
< SERVICE INFORMATION >
C
DE
F
G H
I
K L
M A
B
AT C
N
O P
4.CHECK REAR BLOWER MOTOR RELAY
Turn ignition switch OFF.
Refer to "Rear Blower Motor Relay".
OK or NG
OK >> GO TO 5.
NG >> Replace rear blower motor relay.
5.CHECK REAR BLOWER MOTOR POWER FR OM RELAY TO REAR BLOWER MOTOR
1. Reconnect rear blower motor connector.
2. Disconnect rear blower motor relay J-1.
3. Turn ignition switch ON.
4. Set rear blower switch (front) to any position except OFF, REAR, or 4 - speed.
5. Momentarily (no more than 4 seconds), connect a jumper wire
between rear blower motor relay connector J-1 (harness side)
terminals 3 and 5.
OK or NG
OK >> GO TO 6.
NG >> GO TO 10.
6.CHECK REAR BLOWER MOTOR RELAY (COIL SIDE) POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect fuse block (J/B) connector M39.
3. Turn ignition switch ON.
4. Set rear blower switch (front) to any position except OFF, REAR, or 4 - speed.
5. Check voltage between fuse block (J/B) harness connector M39 terminal 3Q and ground.
OK or NG
OK >> GO TO 7.
NG >> GO TO 20.
7.CHECK REAR BLOWER MOTOR RE LAY (COIL SIDE) GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect fuse block (J/B) connector M3.
3. Check continuity between fuse block (J/B) harness connector M3 terminal 7N and ground.
OK or NG
OK >> Replace fuse block (J/B).
NG >> Repair harness or connector.
8.REPLACE FUSE
Refer to PG-73
Fuse should not open when rear blower motor is activated.
OK or NG
OK >> Inspection End.
NG >> GO TO 9.
9.CHECK REAR BLOWER MOTOR POWER SUPPLY CIRCUIT FOR SHORTRear blower motor should rotate.
WJIA0972E
3Q - Ground : Battery voltage.
LJIA0101E
7N - Ground : Continuity should exist.
WJIA0597E

ATC-90
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
1. Turn ignition switch OFF.
2. Disconnect fuse block (J/B) connector M3 and rear blower motorconnector.
3. Check continuity between rear blower motor harness connector
B134 terminal 2 and ground.
OK or NG
OK >> Check rear blower motor. Refer to ATC-78, "Front
Blower Motor Circuit".
NG >> Repair harness or connector.
10.CHECK REAR BLOWER MOTOR RELAY (SWITCH SIDE) POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect fuse block (J/B) and rear blower motor connectors.
3. Check continuity between fu se block (J/B) harness connector
M3 terminal 3N and 8N and rear blower motor harness connec-
tor B134 terminal 2.
OK or NG
OK >> GO TO 20.
NG >> Repair harness or connector.
11 .CHECK REAR BLOWER MOTOR
Check rear blower motor. Refer to "Rear Blower Motor".
OK or NG
OK >> GO TO 12.
NG >> Replace rear blower motor. refer to ATC-128, "
Removal and Installation"
12.CHECK REAR BLOWER SWITCH (FRONT)
Refer to "Rear Blower Switch (Front)" .
OK or NG
OK >> GO TO 15.
NG >> Replace rear blower switch (front). Refer to ATC-123, "
Removal and Installation"
13.CHECK REAR BLOWER MOTOR RESISTOR
Refer to "Rear Blower Motor Resistor".
OK or NG
OK >> GO TO 14.
NG >> Replace rear blower motor resistor. Refer to ATC-144
14.CHECK REAR BLOWER SWITCH (FRONT) CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect rear blower switch (front) M52.
3. Turn ignition switch ON.
4. Reconnect rear blower motor resistor harness connector B133.
5. Check voltage between each rear blower switch (front) connec- tor M52 terminals 3, 7, and 8, and ground.2 - Ground : Continuity should not exist.
WJIA0598E
3N, 8N - 2 : Continuity should exist.
WJIA0599E
Te r m i n a l N o .
Voltage
(+) (-)
3 Ground Approx. 12V
7
8
LJIA0108E