INFINITI QX56 2004 Factory Service Manual

ATC-86
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
1. CHECK FUSES
Check 20A fuses [No. 24 and 27 (located in the fuse and fusible link box)]. For fuse layout. Refer to PG-77,
"FUSE AND FUSIBLE LINK BOX" .
OK or NG
OK >> GO TO 2.
NG >> GO TO 10.
2. CHECK FRONT BLOWER MOTOR POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front blower motor connector M62.
3. Turn ignition switch ON.
4. Press the MODE switch to select any mode except OFF.
5. Set front fan switch to high.
6. Check voltage between front blower motor harness connector
M62 terminal 2 (W/L) and ground.
OK or NG
OK >> GO TO 12.
NG >> GO TO 3.
3. CHECK FRONT BLOWER MOTOR RELAY (SWITCH SIDE) POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect front blower motor relay M107.
3. Check voltage between front blower motor relay harness con-
nector M107 terminals 5 (GR) and 7 (P), and ground.
OK or NG
OK >> GO TO 4.
NG >> Repair harness or connector.
4. CHECK FRONT BLOWER MOTOR RELAY
Refer to ATC-89, "
Front Blower Motor Relay" .
OK or NG
OK >> GO TO 5.
NG >> Replace front blower motor relay.
5. CHECK FRONT BLOWER MOTOR RELAY (SWITCH SIDE) CIRCUIT FOR OPEN
1. Turn ignition switch OFF.
2. Disconnect blower motor relay connector M107 and front blower
motor connector M62.
3. Check continuity between front blower motor relay harness con-
nector M107 terminals 3 (W/L) and 6 (W/L)
and front blower motor harness connector M62 terminal 2 (W/L).
OK or NG
OK >> GO TO 6.
NG >> Repair harness or connector.2 - Ground : Battery voltage should exist.
WJIA1331E
5, 7 - Ground : Battery voltage should exist.
WJIA0780E
3, 6 - 2 : Continuity should exist.
WJIA0781E

TROUBLE DIAGNOSIS
ATC-87
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
6. CHECK VARIABLE BLOWER CONTROL POWER SUPPLY CIRCUIT FOR OPEN
1. Disconnect variable blower control connector M122.
2. Check continuity between front blower motor relay harness con-
nector M107 terminals 3 (W/L) and 6 (W/L), and variable blower
control harness connector M122 terminal 1 (W/L).
OK or NG
OK >> GO TO 7.
NG >> Repair harness or connector.
7. CHECK VARIABLE BLOWER CONTROL SIGNAL CIRCUIT
1. Disconnect front air control connector M49.
2. Check continuity between front air control harness connector
M49 terminal 13 (G/R) and variable blower control harness con-
nector M122 terminal 2 (G/R).
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 1 (Y/G) 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 harness con-
nector M107 terminal 2 (R/B) and front air control harness con-
nector M49 terminal 26 (R/B).
OK or NG
OK >> Replace front air control. Refer to ATC-135, "FRONT
AIR CONTROL" .
NG >> Repair harness or connector.3, 6 - 1 : Continuity should exist.
WJIA0784E
13 - 2 : Continuity should exist.
WJIA0785E
1 - Ground : Battery voltage should exist.
WJIA0786E
2 - 26 : Continuity should exist.
WJIA0471E

ATC-88
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
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
1. Turn ignition switch OFF.
2. Disconnect variable blower control connector M122.
3. Check continuity between variable blower control harness con-
nector M122 terminal 1 (W/L) 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 M49.
2. Check continuity between front air control harness connector
M49 terminal 13 (G/R) and variable blower control harness con-
nector M122 terminal 2 (G/R).
OK or NG
OK >> Check blower motor, if OK replace variable blower con-
trol. Refer to ATC-89, "
Front Blower Motor" .
NG >> Repair harness or connector.1 - Ground. : Continuity should not exist.
WJIA0788E
13 - 2 : Continuity should exist.
WJIA0785E

TROUBLE DIAGNOSIS
ATC-89
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
COMPONENT INSPECTION
Front Blower Motor Relay
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.
LJIA0068E
WJIA0895E

ATC-90
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Rear Blower Motor CircuitEJS002CJ
SYMPTOM:

Blower motor operation is malfunctioning.
INSPECTION FLOW
*1AT C - 5 9 , "Operational Check (Rear)"*2AT C - 9 9 , "Rear Fan Switch (Front)"*3AT C - 3 5 , "SYMPTOM TABLE"
WJIA0791E

TROUBLE DIAGNOSIS
ATC-91
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
SYSTEM DESCRIPTION
Component Parts
Rear blower speed control system components are:

Front air control

Rear fan switch (front)

Rear fan switch (rear)

Rear blower motor resistor

Rear blower motor

Rear blower motor relay
System Operation
NOTE:
The rear heat or A/C cannot operate unless the front heat or A/C is on.
Rear Blower Control
When the rear fan switch (front) is in the off (O) position, the rear blower motor cannot operate.
When the rear fan switch (front) is in the rear (R) position, it allows the rear fan switch (rear) to control the rear
blower motor speed. In any other position (1-4), the rear fan switch (front) controls the rear blower motor
speed regardless of the rear fan switch (rear) position.
DIAGNOSTIC PROCEDURE FOR REAR BLOWER MOTOR
Rear Fan Switch (Rear) Circuit
SYMPTOM:

Rear blower motor does not rotate when rear fan switch (front) is set to rear (R) position.
WJIA1687E

ATC-92
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
1. CHECK REAR BLOWER MOTOR OPERATION
Blower motor rotates normally when rear fan switch (front) is set at 1 - 4 speed.
OK or NG
OK >> GO TO 2.
NG >> Refer to AT C - 9 3 , "
Trouble Diagnosis Procedure For Rear Blower Motor (1 - 4 Speed)" .
2. CHECK REAR FAN SWITCH (FRONT)
Refer to ATC-99, "
Rear Fan Switch (Front)" .
OK or NG
OK >> GO TO 3.
NG >> Replace rear fan switch (front). Refer to ATC-135, "
FRONT AIR CONTROL"
3. CHECK REAR FAN SWITCH (REAR)
Refer to ATC-99, "
Rear Fan Switch (Rear)" .
OK or NG
OK >> GO TO 4.
NG >> Replace rear fan switch (rear). Refer to ATC-135, "
REAR AIR CONTROL" .
4. CHECK CIRCUIT CONTINUITY
1. Turn ignition switch OFF.
2. Disconnect rear fan switch (front) connector M52 and rear fan
switch (rear) (Rear air control) connector R208.
3. Check voltage between rear fan switch (front) harness connec-
tor M52 terminal 2 (BR) and rear fan switch (rear) (Rear air con-
trol) harness connector R208 terminal 10 (BR).
OK or NG
OK >> Inspection End.
NG >> Repair harness or connector.2 - 10 : Continuity should exist.WJIA0794E

TROUBLE DIAGNOSIS
ATC-93
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
Trouble Diagnosis Procedure For Rear Blower Motor (1 - 4 Speed)
SYMPTOM:

Rear blower motor does not rotate when rear fan switch (front) is set at 1 - 4 speed.
Inspection Flow
*1AT C - 5 9 , "Operational Check (Rear)"*2AT C - 9 3 , "Trouble Diagnosis Proce-
dure For Rear Blower Motor (1 - 4
Speed)"
*3ATC-35, "SYMPTOM TABLE"
WJIA0795E

ATC-94
TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
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-76, "
FUSE BLOCK-JUNCTION
BOX(J/B)" .
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 B134.
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 (L/R) and ground.
OK or NG
OK >> GO TO 11.
NG >> GO TO 4.
4. CHECK REAR BLOWER MOTOR RELAY
Refer to ATC-99, "
Rear Blower Motor Relay" .
OK or NG
OK >> GO TO 5.
NG >> Replace rear blower motor relay.
5. CHECK REAR BLOWER MOTOR POWER FROM RELAY TO REAR BLOWER MOTOR
1. Turn ignition switch OFF.
2. Reconnect rear blower motor connector.
3. Disconnect rear blower motor relay J1.
4. Turn ignition switch ON.
5. Set rear fan switch (front) to any position except off (0), rear (R),
or 4 - speed.
6. Momentarily (no more than 4 seconds), connect a jumper wire
between rear blower motor relay connector J1 terminals 3 and 5.
OK or NG
OK >> GO TO 6.
NG >> GO TO 10.1 - Ground : Battery voltage should exist.
WJIA0596E
Rear blower motor should rotate.LJIA0100E

TROUBLE DIAGNOSIS
ATC-95
C
D
E
F
G
H
I
K
L
MA
B
AT C
Revision: August 20072004 QX56
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 fan switch (front) to any position except off (0), rear (R),
or 4 - speed.
5. Check voltage between fuse block (J/B) harness connector M39
terminal 3Q (W/L) and ground.
OK or NG
OK >> GO TO 7.
NG >> GO TO 20.
7. CHECK REAR BLOWER MOTOR RELAY (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 (B) and ground.
OK or NG
OK >> Replace fuse block (J/B).
NG >> Repair harness or connector.
8. REPLACE FUSE
Refer to PG-76, "
FUSE BLOCK-JUNCTION BOX(J/B)" .
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 SHORT
1. Turn ignition switch OFF.
2. Disconnect battery cables and rear blower motor connector
B134.
3. Check continuity between rear blower motor harness connector
B134 terminal 2 (L/R) and ground.
OK or NG
OK >> Check rear blower motor. Refer to ATC-100, "Rear
Blower Motor" .
NG >> Repair harness or connector.1 - Ground : Battery voltage should exist.
LJIA0101E
7N - Ground : Continuity should exist.
WJIA0597E
2 - Ground : Continuity should not exist.
WJIA0598E