Nissan Pathfinder (2008 year). Manual - part 337

P1572 ASCD BRAKE SWITCH

EC-813

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P1572 ASCD BRAKE SWITCH

Component Description

INFOID:0000000001537932

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-513

 for the ASCD function.

On Board Diagnosis Logic

INFOID:0000000001537933

• This self-diagnosis has the one trip detection logic.
• The MIL will not light up for this self-diagnosis.
NOTE:
• If DTC P 1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-768

.

• 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.

DTC Confirmation Procedure

INFOID:0000000001537934

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
• 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. 

• If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at

least 10 seconds 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.

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-III

1.

Start engine (VDC switch OFF).

2.

Select “DATA MONITOR” mode with CONSULT-III.

3.

Press MAIN switch and make sure that CRUISE indicator lights up.

BBIA0560E

DTC No.

Trouble Diagnosis 

Name

DTC Detecting Condition

Possible Cause

P1572
1572

ASCD brake switch

A)

When the vehicle speed is above 30km/h (19 
MPH), ON signals from the stop lamp switch 
and the ASCD brake switch are sent to 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-814

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P1572 ASCD BRAKE SWITCH

4.

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

5.

Check 1st trip DTC.
If 1st trip DTC is detected, go to 

EC-814, "Diagnosis Procedure"

.

If 1st trip DTC is not detected, go to the following step.

6.

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

7.

Check 1st trip DTC.

8.

If 1st trip DTC is detected, go to 

EC-814, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000001537935

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 voltage between ECM terminal 108 and ground under the
following conditions.

OK or NG

OK

>> GO TO 2.

NG

>> GO TO 3.

2.

CHECK OVERALL FUNCTION-II

 With CONSULT-III

Check “BRAKE SW2” indication in “DATA MONITOR” mode. 

 Without CONSULT-III

VHCL SPEED SE

More than 30 km/h (19 MPH)

Selector lever

Suitable position 

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 condition.

CONDITION

INDICATION

Brake pedal: Slightly depressed

OFF

Brake pedal: Fully released

ON

CONDITION

VOLTAGE

Brake pedal: Slightly depressed

Approximately 0V

Brake pedal: Fully released

Battery voltage

MBIB0061E

CONDITION

INDICATION

Brake pedal: Fully released

OFF

Brake pedal: Slightly depressed

ON

P1572 ASCD BRAKE SWITCH

EC-815

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Check voltage between ECM terminal 101 and ground under the following conditions.

OK or NG

OK

>> GO TO 11.

NG

>> GO TO 7.

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-III 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 E160
• 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 6.

NG

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

CONDITION

VOLTAGE

Brake pedal: Fully released

Approximately 0V

Brake pedal: Slightly depressed

Battery voltage

PBIB1537E

BBIA0560E

Voltage: Battery voltage

PBIB0857E

Continuity should exist.

EC-816

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P1572 ASCD BRAKE SWITCH

6.

CHECK ASCD BRAKE SWITCH

Refer to 

EC-817, "Component Inspection"

.

OK or NG

OK

>> GO TO 11.

NG

>> Replace ASCD brake switch.

7.

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-III or tester.

OK or NG

OK

>> GO TO 9.

NG

>> GO TO 8.

8.

DETECT MALFUNCTIONING PART

Check the following.
• Fuse block (J/B) connector E160
• 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.

9.

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 10.

NG

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

10.

CHECK STOP LAMP SWITCH

Refer to 

EC-817, "Component Inspection"

.

OK or NG

OK

>> GO TO 11.

NG

>> Replace stop lamp switch.

BBIA0560E

Voltage: Battery voltage

PBIB1184E

Continuity should exist.

P1572 ASCD BRAKE SWITCH

EC-817

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11.

CHECK INTERMITTENT INCIDENT

Refer to 

GI-51, "Intermittent Incident"

.

>> INSPECTION END

Component Inspection

INFOID:0000000001537936

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.

If NG, adjust ASCD brake switch installation, refer to 

BR-15,

"Removal and Installation"

, 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.

If NG, adjust stop lamp switch installation, refer to 

BR-15,

"Removal and Installation"

, and perform step 3 again.

Condition

Continuity

Brake pedal: Fully released

Should exist.

Brake pedal: Slightly depressed

Should not exist.

SEC023D

Condition

Continuity

Brake pedal: Fully released

Should not exist.

Brake pedal: Slightly depressed

Should exist.

PBIB1185E

EC-818

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P1574 ASCD VEHICLE SPEED SENSOR

P1574 ASCD VEHICLE SPEED SENSOR

Component Description

INFOID:0000000001537937

The ECM receives two vehicle speed sensor signals via CAN communication line. One is sent from combina-
tion meter and the other is from TCM (Transmission control module). The ECM uses these signals for ASCD
control. Refer to 

EC-513

 for ASCD functions.

On Board Diagnosis Logic

INFOID:0000000001537938

• This self-diagnosis has the one trip detection logic.
• The MIL will not light up for this self-diagnosis.
NOTE:
• If DTC P1574 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC U1000,

U1001. Refer to 

EC-566

.

• If DTC P1574 is displayed with DTC U1010, first perform the trouble diagnosis for DTC U1010. Refer

to 

EC-567

.

• If DTC P1574 is displayed with DTC P0500, first perform the trouble diagnosis for DTC P0500. Refer

to 

EC-757

.

• If DTC P1574 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-768

.

DTC Confirmation Procedure

INFOID:0000000001537939

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
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.

TESTING CONDITION:
Step 3 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.

1.

Start engine (VDC switch OFF).

2.

Drive the vehicle at more than 40 km/h (25 MPH).

3.

Check DTC.

4.

If DTC is detected, go to 

EC-818, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001537940

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

TM-33, "OBD-II Diagnostic Trouble Code (DTC)"

.

OK or NG

OK

>> GO TO 2.

NG

>> Perform trouble shooting relevant to DTC indicated.

2.

CHECK DTC WITH ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)

DTC No.

Trouble Diagnosis 

Name

DTC Detecting Condition

Possible Cause

P1574
1574

ASCD vehicle speed 
sensor

ECM detects a difference between two vehicle 
speed signals is out of the specified range.

• Harness or connectors

(The CAN communication line is open or 
shorted.)

• Combination meter
• ABS actuator and electric unit (control unit)
• Wheel sensor
• TCM
• ECM

P1574 ASCD VEHICLE SPEED SENSOR

EC-819

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Refer to 

BRC-21, "CONSULT-III Function (ABS)"

 or 

BRC-141, "CONSULT-III Function (ABS)"

.

OK or NG

OK

>> GO TO 3.

NG

>> Repair or replace.

3.

CHECK COMBINATION METER FUNCTION

Check combination meter function.
Refer to 

MWI-24, "CONSULT-III Function (METER/M&A)"

.

>> INSPECTION END

EC-820

< COMPONENT DIAGNOSIS >

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P1805 BRAKE SWITCH

P1805 BRAKE SWITCH

Description

INFOID:0000000001537941

Brake switch signal is applied to the ECM through the stop lamp switch when the brake pedal is depressed.
This signal is used mainly to decrease the engine speed when the vehicle is driving.

On Board Diagnosis Logic

INFOID:0000000001537942

The MIL will not light up for this self-diagnosis.

FAIL-SAFE MODE

When the malfunction is detected, the ECM enters fail-safe mode.

DTC Confirmation Procedure

INFOID:0000000001537943

 WITH CONSULT-III

1.

Turn ignition switch ON.

2.

Fully depress the brake pedal for at least 5 seconds.

3.

Erase the DTC with CONSULT-III.

4.

Check 1st trip DTC.

5.

If 1st trip DTC is detected, go to 

EC-820, "Diagnosis Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-III” above.

Diagnosis Procedure

INFOID:0000000001537944

1.

CHECK STOP LAMP SWITCH CIRCUIT

1.

Turn ignition switch OFF.

2.

Check the stop lamp when depressing and releasing the brake pedal.

OK or NG

OK

>> GO TO 4.

NG

>> GO TO 2.

2.

CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT 

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1805
1805

Brake switch

A brake switch signal is not sent to ECM for ex-
tremely long time while the vehicle is driving.

• Harness or connectors

(Stop lamp switch circuit is open or short-
ed.)

• Stop lamp switch

Engine operating condition in fail-safe mode

ECM controls the electric throttle control actuator by regulating the throttle opening to a small range.
Therefore, acceleration will be poor.

Vehicle condition

Driving condition

When engine is idling

Normal

When accelerating

Poor acceleration

Brake pedal

Stop lamp

Fully released

Not illuminated

Depressed

Illuminated