Infiniti QX56 (Z62). Manual - part 617

EC-446

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1572 ICC BRAKE SWITCH

NO

>> GO TO 2.

2.

CHECK ICC BRAKE SWITCH-II

1.

Adjust ICC brake switch installation. Refer to 

BR-21, "Inspection and Adjustment"

.

2.

Check the continuity between ICC brake switch terminals under the following conditions.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace ICC brake switch. Refer to 

BR-20, "Removal and Installation"

.

Component Inspection (Stop Lamp Switch)

INFOID:0000000006217950

1.

CHECK STOP LAMP SWITCH-I

1.

Turn ignition switch OFF.

2.

Disconnect stop lamp switch harness connector.

3.

Check the continuity between stop lamp switch terminals under the following conditions.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 2.

2.

CHECK STOP LAMP SWITCH-II

1.

Adjust stop lamp switch installation. Refer to 

BR-21, "Inspection and Adjustment"

.

2.

Check the continuity between stop lamp switch terminals under the following conditions.

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace stop lamp switch. Refer to 

BR-20, "Removal and Installation"

.

Terminals

Condition

Continuity

1 and 2

Brake pedal

Fully released

Existed

Slightly depressed

Not existed

Terminals

Condition

Continuity

1 and 2

Brake pedal

Fully released

Not existed

Slightly depressed

Existed

Terminals

Condition

Continuity

1 and 2

Brake pedal

Fully released

Not existed

Slightly depressed

Existed

P1574 ASCD VEHICLE SPEED SENSOR

EC-447

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

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P1574 ASCD VEHICLE SPEED SENSOR

Description

INFOID:0000000006288349

The ECM receives two vehicle speed signals by the CAN communication line. One is sent from “combination
meter”, and the other is from TCM (Transmission control module). The ECM uses these signals for ASCD con-
trol. Refer to 

EC-48, "AUTOMATIC SPEED CONTROL DEVICE (ASCD) : System Description"

 for ASCD func-

tions.

DTC Logic

INFOID:0000000006288350

DTC DETECTION LOGIC

NOTE:
• If DTC P1574 is displayed with DTC UXXXX, perform the trouble diagnosis for DTC UXXXX.
• If DTC P1574 is displayed with DTC P0500, perform the trouble diagnosis for DTC P0500. Refer to

EC-356, "DTC Logic"

.

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

EC-376, "DTC Logic"

.

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

EC-378, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

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.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Start engine (VDC switch OFF).

2.

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

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
This procedure 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.

3.

Check DTC.

Is DTC detected?

YES

>> Proceed to 

EC-449, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006288351

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

TM-61, "CONSULT-III Function (TRANSMISSION)"

.

Is the inspection result normal?

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P1574

ASCD VHL SPD SEN
(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

EC-448

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1574 ASCD VEHICLE SPEED SENSOR

YES

>> GO TO 2.

NO

>> Perform Diagnosis Procedure corresponding to the DTC indicated.

2.

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

Refer to 

BRC-40, "CONSULT-III Function"

.

Is the inspection result normal?

YES

>> GO TO 3.

NO

>> Perform Diagnosis Procedure corresponding to the DTC indicated.

3.

CHECK DTC WITH “COMBINATION METER”

Refer to 

MWI-30, "CONSULT-III Function"

.

>> INSPECTION END

P1574 ICC VEHICLE SPEED SENSOR

EC-449

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

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P1574 ICC VEHICLE SPEED SENSOR

Description

INFOID:0000000006288352

The ECM receives two vehicle speed signals by the CAN communication line. One is sent from “combination
meter”, and the other is from TCM (Transmission control module). The ECM uses these signals for ICC con-
trol. Refer to 

CCS-12, "System Description"

 for ICC functions.

DTC Logic

INFOID:0000000006288353

DTC DETECTION LOGIC

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-356, "DTC Logic"

.

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

to 

EC-376, "DTC Logic"

.

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

to 

EC-378, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

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.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Start engine (VDC switch OFF).

2.

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

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
This procedure 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.

3.

Check DTC.

Is DTC detected?

YES

>> Proceed to 

EC-449, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006288354

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

TM-61, "CONSULT-III Function (TRANSMISSION)"

.

Is the inspection result normal?

YES

>> GO TO 2.

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P1574

ASCD VHL SPD SEN
(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