Infiniti FX35, FX50 (S51). Manual - part 721

P1572 ASCD BRAKE SWITCH

EC-425

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

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6.

DETECT MALFUNCTIONING PART

Check the following.
• Harness connectors E106, M6
• Harness for open or short between ECM and ASCD brake switch

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

7.

CHECK ASCD BRAKE SWITCH

Refer to 

EC-426, "Component Inspection (ASCD Brake Switch)"

Is the inspection result normal?

YES

>> GO TO 13.

NO

>> Replace ASCD brake switch.

8.

CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect stop lamp switch harness connector.

3.

Check the voltage between stop lamp switch harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 10.

NO

>> GO TO 9.

9.

DETECT MALFUNCTIONING PART

Check the following.
• Fuse block (J/B) connector E103
• 10 A fuse (No. 7)
• Harness for open or short between stop lamp switch and battery

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

10.

CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Disconnect ECM harness connector.

2.

Check the continuity between stop lamp switch harness connector and ECM harness connector.

3.

Also check harness for short to ground and short to power.

Is the inspection result normal?

YES

>> GO TO 12.

NO

>> GO TO 11.

11.

DETECT MALFUNCTIONING PART

Check the following.
• Fuse block (J/B) connectors E103, M2
• Harness for open or short between ECM and stop lamp switch

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

12.

CHECK STOP LAMP SWITCH

Refer to 

EC-426, "Component Inspection (Stop Lamp Switch)"

.

Stop lamp switch

Ground

Voltage

Connector

Terminal

E110

1

Ground

Battery voltage

Stop lamp switch

ECM

Continuity

Connector

Terminal

Connector

Terminal

E110

2

M107

122

Existed

EC-426

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

P1572 ASCD BRAKE SWITCH

Is the inspection result normal?

YES

>> GO TO 13.

NO

>> Replace stop lamp switch.

13.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-36, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection (ASCD Brake Switch)

INFOID:0000000005237033

1.

CHECK ASCD BRAKE SWITCH-I

1.

Turn ignition switch OFF.

2.

Disconnect ASCD brake switch harness connector.

3.

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> GO TO 2.

2.

CHECK ASCD BRAKE SWITCH-II

1.

Adjust ASCD brake switch installation. Refer to 

BR-19, "Inspection and Adjustment"

.

2.

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

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace ASCD brake switch.

Component Inspection (Stop Lamp Switch)

INFOID:0000000005237034

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-19, "Inspection and Adjustment"

.

2.

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

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

Existed

Slightly depressed

Not existed

Terminals

Condition

Continuity

1 and 2

Brake pedal

Fully released

Not existed

Slightly depressed

Existed

P1572 ASCD BRAKE SWITCH

EC-427

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

C

D

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EC

N

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O

Is the inspection result normal?

YES

>> INSPECTION END

NO

>> Replace stop lamp switch.

Terminals

Condition

Continuity

1 and 2

Brake pedal

Fully released

Not existed

Slightly depressed

Existed

EC-428

< DTC/CIRCUIT DIAGNOSIS >

[VQ35HR]

P1572 ICC BRAKE SWITCH

P1572 ICC BRAKE SWITCH

Description

INFOID:0000000005237035

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

CCS-24, "System Description"

 for the ICC function.

DTC Logic

INFOID:0000000005237036

DTC DETECTION LOGIC

NOTE:
• If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-356, "DTC Logic"

.

• 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 is turned OFF. And even when malfunction A is detected
in two consecutive trips, DTC is not stored in ECM memory.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting the next test.
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.

NOTE:
The procedure for malfunction B is not described. It takes an extremely long time to complete the procedure
for malfunction B. By performing the procedure for malfunction A, the condition that causes malfunction B can
be detected.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

1.

Start engine (VDC switch OFF).

2.

Press MAIN switch and make sure that CRUISE lamp illuminates.

3.

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

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.

4.

Check 1st trip DTC.

DTC No.

Trouble diagnosis 

name

DTC detecting condition

Possible cause

P1572

ICC brake switch

A)

ON signals from the stop lamp switch and 
the ICC brake switch are sent to ECM at 
the same time.

• Harness or connectors

(The stop lamp switch circuit is shorted.)

• Harness or connectors

(The ICC brake switch circuit is shorted.)

• Stop lamp switch
• ICC brake switch
• ICC brake hold relay
• Incorrect stop lamp switch installation
• Incorrect ICC brake switch installation
• ECM

B)

ICC brake switch signal is not sent to ECM 
for extremely long time while the vehicle is 
being driven

VHCL SPEED SE

More than 30 km/h (19 mph)

Selector lever

Suitable position