Infiniti QX56 (JA60). Manual - part 370

 

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Infiniti QX56 (JA60). Manual - part 370

 

 

EC-132

< COMPONENT DIAGNOSIS >

[VK56DE]

P0127 IAT SENSOR

P0127 IAT SENSOR

Component Description

INFOID:0000000005149146

The intake air temperature sensor is built into mass air flow sensor.

The sensor detects intake air temperature and transmits a signal to

the ECM.

The temperature sensing unit uses a thermistor which is sensitive to

the change in temperature. Electrical resistance of the thermistor

decreases in response to the temperature rise.

<Reference data>

*: This data is reference value and is measured between ECM terminal 34 (Intake air
temperature sensor) and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output

voltage. Doing so may result in damage to the ECM's transistor.

Use a ground other than ECM terminals, such as the ground.

On Board Diagnosis Logic

INFOID:0000000005149147

DTC Confirmation Procedure

INFOID:0000000005149148

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure

before conducting the next step.

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Turn ignition switch OFF and wait at least 10 seconds.

CAUTION:

Always drive vehicle at a safe speed.

TESTING CONDITION:

This test may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road

test is expected to be easier, it is unnecessary to lift the vehicle.
1. Wait until engine coolant temperature is less than 96

°C (205°F)

a. Turn ignition switch ON.
b. Select “DATA MONITOR” mode with CONSULT-III.
c.

Check the engine coolant temperature.

d. If the engine coolant temperature is not less than 96

°C (205°F), turn ignition switch OFF and cool down

engine.

• Perform the following steps before engine coolant temperature is above 96

°C (205°F).

BBIA0355E

Intake air temperature

°C (°F)]

Voltage* (V)

Resistance (k

Ω)

25 (77)

3.3

1.800 - 2.200

80 (176)

1.2

0.283 - 0.359

SEF012P

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0127
0127

Intake air temperature 
too high

Rationally incorrect voltage from the sensor is 
sent to ECM, compared with the voltage signal 
from engine coolant temperature sensor.

• Harness or connectors

(The sensor circuit is open or shorted)

• Intake air temperature sensor

P0127 IAT SENSOR

EC-133

< COMPONENT DIAGNOSIS >

[VK56DE]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Start engine.
5. Hold vehicle speed at more than 70 km/h (43 MPH) for 100 consecutive seconds.
6. Check 1st trip DTC.
7. If 1st trip DTC is detected, go to 

EC-133, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000005149149

1.

CHECK GROUND CONNECTIONS

1. Turn ignition switch OFF.

2. Loosen and retighten three ground screws on the body.

Refer to 

EC-85, "Ground Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Repair or replace ground connections.

2.

CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to 

EC-133, "Component Inspection"

.

OK or NG

OK

>> GO TO 3.

NG

>> Replace mass air flow sensor (with intake air temperature sensor).

3.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-35, "How to Check Terminal"

 and 

GI-38, "Intermittent Incident"

.

Refer to 

EC-435, "Wiring Diagram - ENGINE CONTROL SYSTEM -"

.

>> INSPECTION END

Component Inspection

INFOID:0000000005149150

INTAKE AIR TEMPERATURE SENSOR

1. Check resistance between intake air temperature sensor termi-

nals 5 and 6 under the following conditions.

2. If NG, replace mass air flow sensor (with intake air temperature

sensor).

BBIA0354E

Intake air temperature 

°C (°F)]

Resistance (k

Ω)

25 (77)

1.800 - 2.200

BBIA0355E

EC-134

< COMPONENT DIAGNOSIS >

[VK56DE]

P0127 IAT SENSOR

SEF012P

P0128 THERMOSTAT FUNCTION

EC-135

< COMPONENT DIAGNOSIS >

[VK56DE]

C

D

E

F

G

H

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J

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L

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A

EC

N

P

O

P0128 THERMOSTAT FUNCTION

On Board Diagnosis Logic

INFOID:0000000005149151

NOTE:

If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308,

first perform the trouble diagnosis for DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307,

P0308. Refer to 

EC-192, "DTC Confirmation Procedure"

.

Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long

enough.

This is due to a leak in the seal or the thermostat stuck open.

DTC Confirmation Procedure

INFOID:0000000005167702

WITH CONSULT-III

CAUTION:

Always drive vehicle at a safe speed.

NOTE:

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure

before conducting the next step.

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Turn ignition switch ON.

3. Turn ignition switch OFF and wait at least 10 seconds.

TESTING CONDITION:

• For best results, perform at ambient temperature of –10

°C (14°F) or higher.

• For best results, perform at engine coolant temperature of –10

°C (14°F) to 56°C (133°F).

• Before performing the following procedure, do not fill with the fuel.

1. Turn A/C switch OFF.

2. Turn blower fan switch OFF.

3. Turn ignition switch ON.

4. Select “COOLAN TEMP/S” in “DATA MONITOR” mode with CONSULT-III.

5. Check the indication of “COOLAN TEMP/S”.

If it is below 56

°C (133°F), go to following step.

If it is above 56

°C (133°F), cool down the engine to less than 56°C (133°F). Then go to next steps.

6. Start engine.

7. Drive vehicle for 10 consecutive minutes under the following conditions.

If “COOLAN TEMP/S” increases to more than 75

°C (167°F) within 10 minutes, turn ignition switch

OFF because the test result will be OK.

8. Check 1st trip DTC.

9. If 1st trip DTC is detected, go to 

EC-135, "DTC Confirmation Procedure"

.

WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000005149153

1.

CHECK ENGINE COOLANT TEMPERATURE SENSOR

Refer to 

EC-136, "Component Inspection"

.

OK or NG

OK

>> GO TO 2.

NG

>> Replace engine coolant temperature sensor.

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0128
0128

Thermostat function

The engine coolant temperature does not 
reach to specified temperature even though 
the engine has run long enough.

• Thermostat
• Leakage from sealing portion of thermostat
• Engine coolant temperature sensor

VHCL SPEED SE

More than 56 km/h (35 MPH)

 

 

 

 

 

 

 

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