Infiniti QX56 (Z62). Manual - part 615

 

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Infiniti QX56 (Z62). Manual - part 615

 

 

EC-438

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1572 ASCD BRAKE SWITCH

P1572 ASCD BRAKE SWITCH

DTC Logic

INFOID:0000000006217943

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 FOR MALFUNCTION A

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-439, "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
(ASCD brake switch)

A)

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

• Harness or connectors

(The stop lamp switch circuit is shorted.)

• Harness or connectors

(The ASCD brake switch circuit is short-
ed.)

• 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 ve-
hicle is being driven.

Vehicle speed

More than 30 km/h (19 mph)

Selector lever

Suitable position 

P1572 ASCD BRAKE SWITCH

EC-439

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

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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-439, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000006217944

1.

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 as per the following.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> GO TO 3.

2.

CHECK OVERALL FUNCTION-II

 WITH CONSULT-III

Select “BRAKE SW2” and check indication under the following conditions.

 WITHOUT CONSULT-III

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

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
(ASCD brake switch)

Brake pedal

Slightly depressed

OFF

Fully released

ON

ECM

Condition

Voltage (V)

Connector

+

Terminal

Terminal

E80

147

(ASCD brake switch signal)

175

Brake pedal

Slightly depressed

Approx. 0

Fully released

Battery voltage

Monitor item

Condition

Indication

BRAKE SW2
(Stop lamp switch)

Brake pedal

Slightly depressed

ON

Fully released

OFF

EC-440

< DTC/CIRCUIT DIAGNOSIS >

[VK56VD]

P1572 ASCD BRAKE SWITCH

Is the inspection result normal?

YES

>> GO TO 13.

NO

>> GO TO 8.

3.

CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect ASCD brake switch harness connector.

3.

Turn ignition switch ON.

4.

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

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 ASCD 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 ASCD BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between ASCD 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 ECM and ASCD brake switch
• 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 ASCD BRAKE SWITCH

Refer to 

EC-442, "Component Inspection (ASCD Brake Switch)"

Is the inspection result normal?

ECM

Condition

Voltage (V)

Connector

+

Terminal

Terminal

E80

158

(Stop lamp switch signal)

175

Brake pedal

Slightly depressed

Battery voltage

Fully released

Approx. 0

ASCD brake switch

Ground

Voltage

Connector

Terminal

E109

1

Ground

Battery voltage

ASCD brake switch

ECM

Continuity

Connector

Terminal

Connector

Terminal

E109

2

E80

147

Existed

P1572 ASCD BRAKE SWITCH

EC-441

< DTC/CIRCUIT DIAGNOSIS >

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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.
• 10 A fuse (No. 7)
• Harness for open or short between stop lamp switch and battery
• Loose or poor connection for each connector and harness

>> 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.
• Harness for open or short between ECM and stop lamp switch
• Loose or poor connection for each connector and harness

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

12.

CHECK STOP LAMP SWITCH

Refer to 

EC-442, "Component Inspection (Stop Lamp Switch)"

.

Is the inspection result normal?

YES

>> GO TO 13.

NO

>> Replace stop lamp switch.

13.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-40, "Intermittent Incident"

.

>> INSPECTION END

Stop lamp switch

Ground

Voltage

Connector

Terminal

E115

1

Ground

Battery voltage

Stop lamp switch

ECM

Continuity

Connector

Terminal

Connector

Terminal

E115

2

E80

158

Existed

 

 

 

 

 

 

 

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