Infiniti QX56 (JA60). Manual - part 424

EC-348

< COMPONENT DIAGNOSIS >

[VK56DE]

P1572 ASCD BRAKE SWITCH

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

10.

CHECK STOP LAMP SWITCH

Refer to 

EC-348, "Component Inspection"

.

OK or NG

OK

>> GO TO 11.

NG

>> Replace stop lamp switch.

11.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-35, "How to Check Terminal"

 and 

GI-38, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000005149408

ASCD BRAKE SWITCH

1. Turn ignition switch OFF.
2. Disconnect ASCD brake switch harness connector.
3. Check harness continuity between ASCD brake switch terminals

1 and 2 under the following conditions.

If NG, adjust ASCD brake switch installation, refer to 

BR-15,

"Inspection and Adjustment"

, and perform step 3 again.

STOP LAMP SWITCH

1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.
3. Check harness continuity between stop lamp switch terminals 1

and 2 under the following conditions.

If NG, adjust stop lamp switch installation, refer to 

BR-15,

"Inspection and Adjustment"

, and perform step 3 again.

Condition

Continuity

Brake pedal: Fully released

Should exist.

Brake pedal: Slightly depressed

Should not exist.

SEC023D

Condition

Continuity

Brake pedal: Fully released

Should not exist.

Brake pedal: Slightly depressed

Should exist.

PBIB2103E

P1574 ICC VEHICLE SPEED SENSOR

EC-349

< COMPONENT DIAGNOSIS >

[VK56DE]

C

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EC

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P1574 ICC VEHICLE SPEED SENSOR

Component Description

INFOID:0000000005149409

The ECM receives two vehicle speed signals via CAN communication line. One is sent from “unified meter and

A/C amp.”, and the other is from TCM (Transmission control module). The ECM uses these signals for ICC

control. Refer to 

CCS-13

 for ICC functions.

On Board Diagnosis Logic

INFOID:0000000005149410

• This self-diagnosis has the one trip detection logic.

• The MIL will not light up for this self-diagnosis.

NOTE:

• If DTC P1574 is displayed with DTC UXXXX, first perform the trouble diagnosis for DTC UXXXX.

• If DTC P1574 is displayed with DTC P0500, first perform the trouble diagnosis for DTC P0500. Refer

to 

EC-275, "On Board Diagnosis Logic"

.

• If DTC P1574 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-286, "On Board Diagnosis Logic"

.

• If DTC P1574 is displayed with DTC P0607, first perform the trouble diagnosis for DTC P0607. Refer

to 

EC-288, "On Board Diagnosis Logic"

.

DTC Confirmation Procedure

INFOID:0000000005149411

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:

Step 3 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. Start engine.

2. Drive the vehicle at more than 40 km/h (25MPH).

3. Check 1st trip DTC.

4. If DTC is detected, go to 

EC-349, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000005149412

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

TM-30, "OBD-II Diagnostic Trouble Code (DTC)"

.

OK or NG

OK

>> GO TO 2.

NG

>> Perform trouble shooting relevant to DTC indicated.

2.

CHECK DTC WITH “ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)”

Refer to 

BRC-23, "CONSULT-III Function (ABS)"

.

OK or NG

DTC No.

Trouble Diagnosis Name

DTC Detecting Condition

Possible Cause

P1574
1574

ICC vehicle speed sensor

ECM detects a difference between two vehicle 
speed signals is out of the specified range.

• Harness or connectors

(The CAN communication line is open or 
shorted.)

• Combination meter
• ABS actuator and electric unit (control unit)
• Wheel sensor
• TCM
• ECM

EC-350

< COMPONENT DIAGNOSIS >

[VK56DE]

P1574 ICC VEHICLE SPEED SENSOR

OK

>> GO TO 3.

NG

>> Repair or replace.

3.

CHECK COMBINATION METER FUNCTION

Refer to 

MWI-5

.

>> INSPECTION END

P1574 ASCD VEHICLE SPEED SENSOR

EC-351

< COMPONENT DIAGNOSIS >

[VK56DE]

C

D

E

F

G

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EC

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P1574 ASCD VEHICLE SPEED SENSOR

Component Description

INFOID:0000000005149413

The ECM receives two vehicle speed sensor signals via CAN communication line. One is sent from combina-

tion meter and the other is from TCM (Transmission control module). The ECM uses these signals for ASCD

control. Refer to 

EC-33, "System Description"

 for ASCD functions.

On Board Diagnosis Logic

INFOID:0000000005149414

• This self-diagnosis has the one trip detection logic.

• The MIL will not light up for this self-diagnosis.

NOTE:

• If DTC P1574 is displayed with DTC UXXXX, first perform the trouble diagnosis for DTC UXXXX.

• If DTC P1574 is displayed with DTC P0500, first perform the trouble diagnosis for DTC P0500. Refer

to 

EC-275, "On Board Diagnosis Logic"

.

• If DTC P1574 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-286, "On Board Diagnosis Logic"

.

• If DTC P1574 is displayed with DTC P0607, first perform the trouble diagnosis for DTC P0607. Refer

to 

EC-288, "On Board Diagnosis Logic"

.

DTC Confirmation Procedure

INFOID:0000000005149415

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:

Step 3 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. Start engine (VDC switch OFF).

2. Drive the vehicle at more than 40 km/h (25 MPH).

3. Check DTC.

4. If DTC is detected, go to 

EC-351, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000005149416

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

TM-30, "OBD-II Diagnostic Trouble Code (DTC)"

.

OK or NG

OK

>> GO TO 2.

NG

>> Perform trouble shooting relevant to DTC indicated.

2.

CHECK DTC WITH ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)

Refer to 

BRC-23, "CONSULT-III Function (ABS)"

.

DTC No.

Trouble Diagnosis 

Name

DTC Detecting Condition

Possible Cause

P1574
1574

ASCD vehicle speed 
sensor

ECM detects a difference between two vehicle 
speed signals is out of the specified range.

• Harness or connectors

(The CAN communication line is open or 
shorted.)

• Combination meter
• ABS actuator and electric unit (control unit)
• Wheel sensor
• TCM
• ECM