Infiniti QX56 (Z62). Manual - part 796

B2578, B2579 FRONT IN-VEHICLE SENSOR

HAC-75

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONING]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

YES

>> GO TO 3.

NO

>> Repair harness or connector.

3.

CHECK FRONT IN-VEHICLE SENSOR 

Check front in-vehicle sensor. Refer to 

HAC-107, "Component Inspection"

.

Is the inspection result normal?

YES

>> Replace A/C auto amp.. Refer to 

HAC-146, "Removal and Installation"

.

NO

>> Replace front in-vehicle sensor. Refer to 

HAC-148, "FRONT A/C UNIT ASSEMBLY : Removal

and Installation"

.

4.

CHECK FRONT IN-VEHCLE SENSOR POWER SUPPLY CIRCUIT FOR OPEN

1.

Turn ignition switch OFF.

2.

Disconnect A/C auto amp. connector.

3.

Check continuity between front in-vehicle sensor harness connector and A/C auto amp. harness connec-
tor.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> Repair harness or connector.

5.

CHECK FRONT IN-VEHCLE SENSOR POWER SUPPLY CIRCUIT FOR GROUND SHORT

Check continuity between front in-vehicle sensor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Repair harness or connector.

6.

CHECK FRONT IN-VEHICLE SENSOR POWER SUPPLY CIRCUIT FOR POWER SHORT

1.

Turn ignition switch ON.

2.

Check voltage between front in-vehicle sensor harness connector and ground.

Is the inspection result normal?

YES

>> Replace A/C auto amp.. Refer to 

HAC-146, "Removal and Installation"

.

NO

>> Repair harness or connector.

Component Inspection

INFOID:0000000006275911

1.

CHECK FRONT IN-VEHICLE SENSOR

1.

Turn ignition switch OFF.

2.

Disconnect front in-vehicle sensor connector.

3.

Check resistance between front in-vehicle sensor terminals.

Front in-vehicle sensor

A/C auto amp.

Continuity

Connector

Terminal

Connector

Terminal

M73

1

M50

27

Existed

Front in-vehicle sensor

—

Continuity

Connector

Terminal

M73

1

Ground

Not existed

+

−

Voltage

(Approx.)

Front in-vehicle sensor

Connector

Terminal

M73

1

Ground

0 V

HAC-76

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONING]

B2578, B2579 FRONT IN-VEHICLE SENSOR

Is the inspection result normal?

YES

>> INSPECTION END 

NO

>> Replace front in-vehicle sensor. Refer to 

HAC-148, "FRONT A/C UNIT ASSEMBLY : Removal

and Installation"

.

Terminal

Condition

Resistance: k

Ω

Temperature: 

°

C (

°

F)

1

2

−

15 (5)

12.73

−

10 (14)

9.92

−

5 (23)

7.80

0 (32)

6.19

5 (41)

4.95

10 (50)

3.99

15 (59)

3.24

20 (68)

2.65

25 (77)

2.19

30 (86)

1.81

35 (95)

1.51

40 (104)

1.27

45 (113)

1.07

B257B, B257C AMBIENT SENSOR

HAC-77

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONING]

C

D

E

F

G

H

J

K

L

M

A

B

HAC

N

O

P

B257B, B257C AMBIENT SENSOR

DTC Logic

INFOID:0000000006275912

DTC DETECTION LOGIC 

NOTE:
• If DTC is displayed along with DTC U1000, first perform the trouble diagnosis for DTC U1000. Refer to 

HAC-

72, "DTC Logic"

.

• If DTC is displayed along with DTC U1010, first perform the trouble diagnosis for DTC U1010. 

HAC-73,

"DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT-III

1.

Turn ignition switch ON.

2.

Select “Self Diagnostic Result” mode of “HVAC” using CONSULT-III.

3.

Check DTC.

Is DTC detected?

YES

>> Refer to 

HAC-77, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006275913

1.

CHECK AMBIENT SENSOR POWER SUPPLY

1.

Turn ignition switch OFF.

2.

Disconnect ambient sensor connector.

3.

Turn ignition switch ON.

4.

Check voltage between ambient sensor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> GO TO 4.

2.

CHECK AMBIENT SENSOR GROUND CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect A/C auto amp.connector.

3.

Check continuity between ambient sensor harness connector and A/C auto amp. harness connector.

Is the inspection result normal?

DTC

Items

(CONSULT-III screen terms)

DTC detection condition

Possible cause

B257B

AMBIENT SENSOR

The ambient sensor recognition temperature is 
too high.

• Ambient sensor
• A/C auto amp.
• Harness or connectors

(The sensor circuit is open or short-
ed.)

B257C

The ambient sensor recognition temperature is 
too low.

+

−

Voltage

(Approx.)

Ambient sensor

Connector

Terminal

E76

1

Ground

5 V

Ambient sensor

—

Continuity

Connector

Terminal

E76

2

Ground

Existed

HAC-78

< DTC/CIRCUIT DIAGNOSIS >

[AUTOMATIC AIR CONDITIONING]

B257B, B257C AMBIENT SENSOR

YES

>> GO TO 3.

NO

>> Repair harness or connector.

3.

CHECK AMBIENT SENSOR 

Check ambient sensor. Refer to 

HAC-78, "Component Inspection"

.

Is the inspection result normal?

YES

>> Replace A/C auto amp.. Refer to 

HAC-146, "Removal and Installation"

.

NO

>> Replace ambient sensor. Refer to 

HAC-147, "Removal and Installation"

.

4.

CHECK AMBIENT SENSOR POWER SUPPLY CIRCUIT FOR OPEN

1.

Turn ignition switch OFF.

2.

Disconnect A/C auto amp.connector.

3.

Check continuity between ambient sensor harness connector and A/C auto amp. harness connector.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> Repair harness or connector.

5.

CHECK AMBIENT SENSOR POWER SUPPLY CIRCUIT FOR GROUND SHORT

Check continuity between ambient sensor harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 6.

NO

>> Repair harness or connector.

6.

CHECK AMBIENT SENSOR POWER SUPPLY CIRCUIT FOR POWER SHORT

1.

Turn ignition switch ON.

2.

Check voltage between ambient sensor harness connector and ground.

Is the inspection result normal?

YES

>> Replace A/C auto amp.. Refer to 

HAC-146, "Removal and Installation"

.

NO

>> Repair harness or connector.

Component Inspection

INFOID:0000000006275914

1.

CHECK AMBIENT SENSOR

1.

Turn ignition switch OFF.

2.

Disconnect ambient sensor connector.

3.

Check resistance between ambient sensor terminals.

Ambient sensor

A/C auto amp.

Continuity

Connector

Terminal

Connector

Terminal

E76

1

M50

7

Existed

Ambient sensor

—

Continuity

Connector

Terminal

E76

1

Ground

Not existed

+

−

Voltage

(Approx.)

Ambient sensor

Connector

Terminal

E76

1

Ground

0 V