2011 INFINITI QX56 brake

P1572 ASCD BRAKE SWITCHEC-441
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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YES >> GO TO 13.
NO >> Replace ASCD brake switch.
8.CHECK STOP LAMP SWIT
CH 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 SI GNAL 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
Revision: 2010 May2011 QX56

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 s witch 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 s witch 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
Revision: 2010 May2011 QX56

P1572 ICC BRAKE SWITCHEC-443
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P1572 ICC BRAKE SWITCH
DTC LogicINFOID:0000000006217947
DTC DETECTION LOGIC
NOTE:

If DTC P1572 is displayed with DT C 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 tu rned 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 ta kes an extremely long time to complete the procedure
for malfunction B. By performing the procedure for malf unction 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 i ndicator is displayed in combination meter.
3. Drive the vehicle for at least 5 consec utive seconds under the following conditions.
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
This procedure may be conducted with the drive wheel s 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 consec utive 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
Revision: 2010 May2011 QX56

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 wheel
s 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 ProcedureINFOID: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 “DAT A 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 pedalSlightly depressed OFF
Fully released ON
ECM Condition Voltage (V)
Connector +–
Te r m i n a l Te r m i n a l
E80 147
(ICC brake switch signal) 175 Brake pedalSlightly depressed Approx. 0
Fully released Battery voltage
ICC brake switch
Ground Voltage
Connector Terminal
E68 1 Ground Battery voltage
Revision: 2010 May2011 QX56

P1572 ICC BRAKE SWITCHEC-445
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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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 SIGN AL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check the continuity between ICC brake sw itch 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
Revision: 2010 May2011 QX56

EC-446
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1572 ICC BRAKE SWITCH
NO >> GO TO 2.
2.CHECK ICC BRAKE SWITCH-II
1. Adjust ICC brake switch installation. Refer to BR-21, "
Inspection and Adjustment".
2. Check the continuity between ICC brake s witch terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace ICC brake switch. Refer to BR-20, "
Removal and Installation".
Component Inspection (Stop Lamp Switch)INFOID:0000000006217950
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 Not existed
Slightly depressed Existed
Terminals Condition Continuity
1 and 2 Brake pedal Fully released Not existed
Slightly depressed Existed
Revision: 2010 May2011 QX56

P1805 BRAKE SWITCHEC-455
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
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P1805 BRAKE SWITCH
DTC LogicINFOID:0000000006217957
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Fully depress the brake pedal for at least 5 seconds.
3. Erase the DTC.
4. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-455, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217958
1.CHECK STOP LAMP SWITCH CIRCUIT
1. Turn ignition switch OFF.
2. Check for stop lamp illumination under the following conditions.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK STOP LAMP SWIT CH POWER SUPPLY CIRCUIT
1. Disconnect stop lamp switch harness connector.
2. Check the voltage between stop lamp switch harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.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.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1805 BRAKE SW/CIRCUIT
(Brake switch) A brake switch signal is not sent to ECM
for extremely long time while the vehicle
is being driven.  Harness or connectors
(Stop lamp switch circuit is open or shorted.)
 Stop lamp switch
Condition Stop lamp
Brake pedal Fully released Not illuminated
Slightly depressed Illuminated
Stop lamp switch Ground Voltage
Connector Terminal
E115 1 Ground Battery voltage
Revision: 2010 May2011 QX56

EC-456
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1805 BRAKE SWITCH
4.CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect stop lamp switch harness connector.
2. Disconnect ECM harness connector.
3. Check the continuity between stop lamp s witch 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 6.
NO >> GO TO 5.
5.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.
6.CHECK STOP LAMP SWITCH
Refer to EC-456, "
Component Inspection (Stop Lamp Switch)".
Is the inspection result normal?
YES >> GO TO 7.
NO >> Replace stop lamp switch. Refer to BR-20, "
Removal and Installation".
7.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
Component Inspection (Stop Lamp Switch)INFOID:0000000006217959
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?
Stop lamp switch ECM Continuity
Connector Terminal Connector Terminal
E115 2 E80 158 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
Revision: 2010 May2011 QX56