Infiniti Q45. Manual - part 493

DTC P1572 ASCD BRAKE SWITCH

EC-611

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11. 

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors M401, M61

●

Harness connectors M135, F105

●

Harness for open or short between ECM and stop lamp switch

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

12. 

CHECK STOP LAMP SWITCH

Refer to 

EC-611, "Component Inspection"

  

OK or NG

OK

>> GO TO 13.

NG

>> Replace stop lamp switch.

13. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-145, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END

Component Inspection

NBS0024P

ASCD BRAKE SWITCH

1.

Turn ignition switch OFF.

2.

Disconnect ASCD brake switch harness connector.

3.

Check continuity between ASCD brake switch terminals 1 and 2
under the following conditions.

If NG, adjust ASCD brake switch installation, refer to 

BR-6,

"BRAKE PEDAL"

 , and perform step 3 again.

STOP LAMP SWITCH

1.

Turn ignition switch OFF.

2.

Disconnect stop lamp switch harness connector.

3.

Check continuity between stop lamp switch terminals 3 and 4
under the following conditions.

If NG, adjust stop lamp switch installation, refer to 

BR-6,

"BRAKE PEDAL"

 , and perform step 3 again.

Condition

Continuity

When brake pedal: Fully released.

Should exist.

When brake pedal: Slightly depressed.

Should not exist.

PBIB1536E

Condition

Continuity

When brake pedal: Fully released.

Should not exist.

When brake pedal: Slightly depressed.

Should exist.

PBIB2103E

EC-612

DTC P1574 ICC VEHICLE SPEED SENSOR

DTC P1574 ICC VEHICLE SPEED SENSOR

PFP:31036

Component Description

NBS0024Q

The ECM receives two vehicle speed signals via 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 control.
Refer to 

ACS-6, "DESCRIPTION"

  for ICC functions.

On Board Diagnosis Logic

NBS0024R

This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.

NOTE:

●

If DTC P1574 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to 

EC-156, "DTC U1000, U1001 CAN COMMUNICATION LINE"

 .

●

If DTC P1574 is displayed with DTC U1010, first perform the trouble diagnosis for DTC U1010.
Refer to 

EC-159, "DTC U1010 CAN COMMUNICATION"

 .

●

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

EC-474, "DTC P0500 VSS"

 .

●

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

EC-489, "DTC P0605 ECM"

 .

DTC Confirmation Procedure

NBS0024S

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
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.

 WITH CONSULT-II

1.

Start engine (VDC switch OFF).

2.

Select “DATA MONITOR” mode with CONSULT-II.

3.

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

4.

If DTC is detected, go to 

EC-613, "Diagnostic Procedure"

 .

 WITH GST

Follow the procedure “WITH CONSULT-II” above.

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

●

VDC/TCS/ABS control unit

●

Wheel sensor

●

TCM

●

ECM

SEF058Y

DTC P1574 ICC VEHICLE SPEED SENSOR

EC-613

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Diagnostic Procedure

NBS0024T

1. 

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

AT-38, "ON BOARD DIAGNOSTIC (OBD) SYSTEM"

 .

OK or NG

OK

>> GO TO 2.

NG

>> Perform trouble shooting relevant to DTC indicated.

2. 

CHECK DTC WITH VDC/TCS/ABS CONTROL UNIT

Refer to 

BRC-10, "TROUBLE DIAGNOSIS"

 .

OK or NG

OK

>> GO TO 3.

NG

>> Repair or replace.

3. 

CHECK COMBINATION METER

Check combination meter function.
Refer to 

DI-7, "COMBINATION METERS"

 .

>> INSPECTION END

EC-614

DTC P1574 ASCD VEHICLE SPEED SENSOR

DTC P1574 ASCD VEHICLE SPEED SENSOR

PFP:31036

Component Description

NBS0024U

The ECM receives two vehicle speed signals via 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-29, "AUTOMATIC SPEED CONTROL DEVICE (ASCD)"

  for ASCD functions.

On Board Diagnosis Logic

NBS0024V

This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.

NOTE:

●

If DTC P1574 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to 

EC-156, "DTC U1000, U1001 CAN COMMUNICATION LINE"

 .

●

If DTC P1574 is displayed with DTC U1010, first perform the trouble diagnosis for DTC U1010.
Refer to 

EC-159, "DTC U1010 CAN COMMUNICATION"

 .

●

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

EC-474, "DTC P0500 VSS"

 .

●

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

EC-489, "DTC P0605 ECM"

 .

DTC Confirmation Procedure

NBS0024W

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
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.

 WITH CONSULT-II

1.

Start engine (VDC switch OFF).

2.

Select “DATA MONITOR” mode with CONSULT-II.

3.

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

4.

If DTC is detected, go to 

EC-615, "Diagnostic Procedure"

 .

 WITH GST

Follow the procedure “WITH CONSULT-II” above.

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

●

VDC/TCS/ABS control unit

●

Wheel sensor

●

TCM

●

ECM

SEF058Y