Infiniti QX56 (Z62). Manual - part 616

EC-442

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1572 ASCD BRAKE SWITCH

Component Inspection (ASCD Brake Switch)

INFOID:0000000006217945

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-21, "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. Refer to 

BR-20, "Removal and Installation"

.

Component Inspection (Stop Lamp Switch)

INFOID:0000000006217946

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

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

P1572 ICC BRAKE SWITCH

EC-443

< DTC/CIRCUIT DIAGNOSIS >

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P1572 ICC BRAKE SWITCH

DTC Logic

INFOID:0000000006217947

DTC DETECTION LOGIC

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

to 

EC-376, "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

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

1.

Start engine (VDC switch OFF).

2.

Press MAIN switch and check that CRUISE indicator is displayed in combination meter.

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.

Is 1st trip DTC detected?

YES

>> Go to 

EC-444, "Diagnosis Procedure"

.

NO

>> GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE

1.

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

CAUTION:

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P1572

ASCD BRAKE SW
(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

Vehicle speed

More than 30 km/h (19 mph)

Selector lever

Suitable position 

EC-444

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1572 ICC BRAKE SWITCH

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.

2.

Check 1st trip DTC.

Is 1st trip DTC detected?

YES

>> Go to 

EC-444, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006217948

1.

CHECK DTC WITH ADAS CONTROL UNIT

Refer to 

DAS-21, "CONSULT-III Function (ICC/ADAS)"

 and 

DAS-38, "DTC Index"

.

Are any DTCs detected?

YES

>> Perform the Diagnosis Procedure corresponding to the detected DTC.

NO

>> GO TO 2.

2.

CHECK OVERALL FUNCTION-I

 WITH CONSULT-III

1.

Turn ignition switch ON.

2.

Select “BRAKE SW1” in “DATA MONITOR” mode with CONSULT-III.

3.

Check “BRAKE SW1” indication under the following conditions.

 WITHOUT CONSULT-III

1.

Turn ignition switch ON.

2.

Check the voltage between ECM harness connector terminals under the following conditions.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> GO TO 3.

3.

CHECK ICC BRAKE SWITCH POWER SUPPLY CIRCUIT-I

1.

Turn ignition switch OFF.

2.

Disconnect ICC brake switch harness connector.

3.

Turn ignition switch ON.

4.

Check the voltage between ICC brake switch harness connector and ground.

Vehicle speed

More than 30 km/h (19 mph)

Selector lever

Suitable position 

Driving location

Depress the brake pedal for more than 5 seconds so as 
not to come off from the above-mentioned vehicle speed.

Monitor item

Condition

Indication

BRAKE SW1
(ICC brake switch)

Brake pedal

Slightly depressed

OFF

Fully released

ON

ECM

Condition

Voltage (V)

Connector

+

–

Terminal

Terminal

E80

147

(ICC brake switch signal)

175

Brake pedal

Slightly depressed

Approx. 0

Fully released

Battery voltage

ICC brake switch

Ground

Voltage

Connector

Terminal

E68

1

Ground

Battery voltage

P1572 ICC BRAKE SWITCH

EC-445

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Is the inspection result normal?

YES

>> GO TO 5.

NO

>> GO TO 4.

4.

DETECT MALFUNCTIONING PART

Check the following.
• 10 A fuse (No. 3)
• Harness for open or short between ICC brake switch and fuse
• Loose or poor connection for each connector and harness

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

5.

CHECK ICC BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between ICC brake switch harness connector and ECM harness connector.

4.

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

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> GO TO 6.

6.

DETECT MALFUNCTIONING PART

Check the following.
• Harness for open or short between ICC brake switch and ECM
• Loose or poor connection for each connector and harness

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

7.

CHECK ICC BRAKE SWITCH

Refer to 

EC-445, "Component Inspection (ICC Brake Switch)"

.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Replace ICC brake switch.

8.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-40, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection (ICC Brake Switch)

INFOID:0000000006217949

1.

CHECK ICC BRAKE SWITCH-I

1.

Turn ignition switch OFF.

2.

Disconnect ICC brake switch harness connector.

3.

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

Is the inspection result normal?

YES

>> INSPECTION END

ICC brake switch

ECM

Continuity

Connector

Terminal

Connector

Terminal

E68

2

E80

147

Existed

Terminals

Condition

Continuity

1 and 2

Brake pedal

Fully released

Existed

Slightly depressed

Not existed