2007 INFINITI FX35 brake

DTC P1572 ASCD BRAKE SWITCH EC-1215
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Revision: 2006 July 2007 FX35/FX45
DTC P1572 ASCD BRAKE SWITCHPFP:25320
Component DescriptionNBS004EH
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-697, "
AUTOMATIC SPEED CONTROL DEVICE
(ASCD)" for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeNBS004EI
Specification data are reference values.
On Board Diagnosis LogicNBS004EJ
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.
NOTE:

If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605.
Refer to EC-1148, "
DTC P0605 ECM" .

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.
PBIB2558E
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 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 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.

EC-1216
[VK45DE]
DTC P1572 ASCD BRAKE SWITCH
Revision: 2006 July 2007 FX35/FX45
DTC Confirmation ProcedureNBS004EK
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.
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-II
1. Start engine (VDC switch OFF).
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Press MAIN switch and make sure that CRUISE lamp lights up.
4. Drive the vehicle for at least 5 consecutive seconds under the following conditions.
If 1st trip DTC is detected, go to EC-1218, "
Diagnostic Proce-
dure" .
If 1st trip DTC is not detected, go to the following step.
5. Drive the vehicle for at least 5 consecutive seconds under the following conditions.
6. If 1st trip DTC is detected, go to EC-1218, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-II” above.
VHCL SPEED SE More than 30 km/h (19 MPH)
Selector lever Suitable position
PBIB2386E
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.

DTC P1572 ASCD BRAKE SWITCH EC-1217
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Revision: 2006 July 2007 FX35/FX45
Wiring Diagram NBS004EL
TBWM1352E

EC-1218
[VK45DE]
DTC P1572 ASCD BRAKE SWITCH
Revision: 2006 July 2007 FX35/FX45
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.
Diagnostic ProcedureNBS004EM
1. CHECK OVERALL FUNCTION-I
With CONSULT-II
1. Turn ignition switch ON.
2. Select “BRAKE SW1” in “DATA MONITOR” mode with CONSULT-II.
3. Check “BRAKE SW1” indication under the following conditions.
Without CONSULT-II
1. Turn ignition switch ON.
2. Check voltage between ECM terminal 108 and ground under the following conditions.
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
TER-
MINAL NO. WIRE
COLOR ITEM CONDITION DATA (DC Voltage)
101 P/L Stop lamp switch [Ignition switch: OFF]

Brake pedal: Fully released
Approximately 0V
[Ignition switch: OFF]

Brake pedal: Slightly depressed BATTERY VOLTAGE
(11 - 14V)
108 SB ASCD brake switch [Ignition switch: ON]

Brake pedal: Slightly depressed
Approximately 0V
[Ignition switch: ON]

Brake pedal: Fully released BATTERY VOLTAGE
(11 - 14V)
CONDITION INDICATION
When brake pedal: Slightly depressed OFF
When brake pedal: Fully released ON
SEC011D
CONDITION VOLTAGE
When brake pedal: Slightly depressed Approximately 0V
When brake pedal: Fully released Battery voltage
MBIB0061E

DTC P1572 ASCD BRAKE SWITCH EC-1219
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Revision: 2006 July 2007 FX35/FX45
2. CHECK OVERALL FUNCTION-II
With CONSULT-II
Check “BRAKE SW2” indication in “DATA MONITOR” mode.
Without CONSULT-II
Check voltage between ECM terminal 101 and ground under the following conditions.
OK or NG
OK >> GO TO 13.
NG >> GO TO 8.
CONDITION INDICATION
When brake pedal: Fully released OFF
When brake pedal: Slightly depressed ON
SEC013D
CONDITION VOLTAGE
When brake pedal: Fully released Approximately 0V
When brake pedal: Slightly depressed Battery voltage
PBIB1537E

EC-1220
[VK45DE]
DTC P1572 ASCD BRAKE SWITCH
Revision: 2006 July 2007 FX35/FX45
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 voltage between ASCD brake switch terminal 1 and ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
4. DETECT MALFUNCTIONING PART
Check the following.

Fuse block (J/B) connector E201

10A fuse

Harness for open or short between ASCD brake switch and fuse
>> Repair open circuit or short to ground or short to power 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 harness continuity between ECM terminal 108 and ASCD brake switch terminal 2. Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
6. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors E211, M41

Harness for open or short between ECM and ASCD brake switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
PBIB2558E
Voltage: Battery voltage
PBIB0857E
Continuity should exist.

DTC P1572 ASCD BRAKE SWITCH EC-1221
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Revision: 2006 July 2007 FX35/FX45
7. CHECK ASCD BRAKE SWITCH
Refer to EC-1222, "
Component Inspection"
OK or NG
OK >> GO TO 13.
NG >> 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 voltage between stop lamp switch terminal 1 and ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 10.
NG >> GO TO 9.
9. DETECT MALFUNCTIONING PART
Check the following.

Fuse block (J/B) connector E201

10A fuse

Harness for open or short between stop lamp switch and battery
>> Repair open circuit or 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 harness continuity between ECM terminal 101 and stop lamp switch terminal 2. Refer to Wiring Diagram.
3. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 12.
NG >> GO TO 11.
PBIB2558E
Voltage: Battery voltage
PBIB1184E
Continuity should exist.

EC-1222
[VK45DE]
DTC P1572 ASCD BRAKE SWITCH
Revision: 2006 July 2007 FX35/FX45
11 . DETECT MALFUNCTIONING PART
Check the following.

Harness connectors E211, M41

Harness for open or short between ECM and stop lamp switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
12. CHECK STOP LAMP SWITCH
Refer to EC-1222, "
Component Inspection"
OK or NG
OK >> GO TO 13.
NG >> Replace stop lamp switch.
13. CHECK INTERMITTENT INCIDENT
Refer to EC-812, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>> INSPECTION END
Component InspectionNBS004EN
ASCD BRAKE SWITCH
1. Turn ignition switch OFF.
2. Disconnect ASCD brake switch harness connector.
3. Check harness continuity between ASCD brake switch terminals 1 and 2 under the following conditions.
4. If NG, adjust ASCD brake switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 3 again.
STOP LAMP SWITCH
1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.
3. Check harness continuity between stop lamp switch terminals 1 and 2 under the following conditions.
4. If NG, adjust stop lamp switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 3 again.
Condition Continuity
Brake pedal: Fully released Should exist
Brake pedal: Slightly depressed Should not exist
PBIB1536E
Condition Continuity
Brake pedal: Fully released Should not exist
Brake pedal: Slightly depressed Should exist
PBIB1535E