Infiniti FX35 / FX45. Manual - part 428

DTC P1572 ICC BRAKE SWITCH

EC-473

< SERVICE INFORMATION >

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2.

Check continuity between relay terminals 3 and 4, 6 and 7 under
the following conditions.

3.

If NG, replace ICC brake hold relay.

Condition

Between terminals

Continuity

12V direct current supply 
between terminals 1 and 2

3 and 4

Should not exist

6 and 7

Should exist

No current supply

3 and 4

Should exist

6 and 7

Should not exist

MBIB0063E

EC-474

< SERVICE INFORMATION >

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DTC P1572 ASCD BRAKE SWITCH

DTC P1572 ASCD BRAKE SWITCH

Component Description

INFOID:0000000001326337

When the brake pedal is depressed, ASCD brake switch is turned
OFF and stop lamp switch is turned ON. ECM detects the state of
the brake pedal by this input of two kinds (ON/OFF signal).
Refer to 

EC-37

 for the ASCD function.

CONSULT-III Reference Value in Data Monitor Mode

INFOID:0000000001326338

Specification data are reference values.

On Board Diagnosis Logic

INFOID:0000000001326339

• This self-diagnosis has the one trip detection logic.
• The MIL will not light up for this self-diagnosis.
NOTE:
• If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-422

• This self-diagnosis has the one trip detection logic. When malfunction A is detected, DTC is not

stored in ECM memory. And in that case, 1st trip DTC and 1st trip freeze frame data are displayed.
1st trip DTC is erased when ignition switch OFF. And even when malfunction A is detected in two
consecutive trips, DTC is not stored in ECM memory.

DTC Confirmation Procedure

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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.

• Procedure for malfunction B is not described here. It takes extremely long time to complete procedure for

malfunction B. By performing procedure for malfunction A, the incident that causes malfunction B can be
detected. 

PBIB1605E

MONITOR ITEM

CONDITION

SPECIFICATION

BRAKE SW1
(ASCD brake switch)

• Ignition switch: ON

Brake pedal: Fully released

ON

Brake pedal: Slightly depressed

OFF

BRAKE SW2
(Stop lamp switch)

• Ignition switch: ON

Brake pedal: Fully released

OFF

Brake pedal: Slightly depressed

ON

DTC No.

Trouble Diagnosis 

Name

DTC Detecting Condition

Possible Cause

P1572
1572

ASCD brake switch

A)

When the vehicle speed is above 30km/h (19 
MPH), ON signals from the stop lamp switch 
and the ASCD brake switch are sent to ECM 
at the same time.

• Harness or connectors

(Stop lamp switch circuit is shorted.)

• Harness or connectors

(ASCD brake switch circuit is shorted.)

• Stop lamp switch
• ASCD brake switch
• Incorrect stop lamp switch installation
• Incorrect ASCD brake switch installation
• ECM

B)

ASCD brake switch signal is not sent to ECM 
for extremely long time while the vehicle is 
driving

DTC P1572 ASCD BRAKE SWITCH

EC-475

< SERVICE INFORMATION >

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TESTING CONDITION:
Steps 4 and 5 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-III

1.

Start engine.

2.

Select “DATA MONITOR” mode with CONSULT-III.

3.

Press MAIN switch and make sure that CRUISE indicator lights up.

4.

Drive the vehicle for at least 5 consecutive seconds under the following condition.

5.

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

EC-477, "Diagnosis Procedure"

.

If 1st trip DTC is not detected, go to the following step.

6.

Drive the vehicle for at least 5 consecutive seconds under the following condition.

7.

Check 1st trip DTC.

8.

If 1st trip DTC is detected, go to 

EC-477, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

VHCL SPEED SE

More than 30 km/h (19 MPH)

Selector lever

Suitable position 

VHCL SPEED SE

More than 30 km/h (19 MPH)

Selector lever

Suitable position 

Driving location

Depress the brake pedal for more than 
five seconds so as not to come off from 
the above-mentioned vehicle speed.

EC-476

< SERVICE INFORMATION >

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DTC P1572 ASCD BRAKE SWITCH

Wiring Diagram

INFOID:0000000001326341

Specification data are reference values and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

TBWM1402E