Infiniti QX56 (JA60). Manual — part 423
EC-344
< COMPONENT DIAGNOSIS >
[VK56DE]
P1572 ASCD BRAKE SWITCH
P1572 ASCD BRAKE SWITCH
Component Description
INFOID:0000000005149404
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).
for the ASCD function.
On Board Diagnosis Logic
INFOID:0000000005149405
• 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
EC-286, "On Board Diagnosis 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 OFF. And even when malfunction A is detected in two
consecutive trips, DTC is not stored in ECM memory.
DTC Confirmation Procedure
INFOID:0000000005149406
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 perform the following procedure
before conducting 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:
Steps 3 and 6 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. Press MAIN switch and make sure that CRUISE indicator lights up.
3. Drive the vehicle for at least 5 consecutive seconds under the following condition.
BBIA0373E
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
P1572 ASCD BRAKE SWITCH
EC-345
< COMPONENT DIAGNOSIS >
[VK56DE]
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4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to
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
Diagnosis Procedure
INFOID:0000000005149407
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.
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
EC-346
< COMPONENT DIAGNOSIS >
[VK56DE]
P1572 ASCD BRAKE SWITCH
Without CONSULT-III
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.
• Harness connectors M31, E152
• Fuse block (J/B) connector M4
• 10 A fuse (No. 15)
• 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.
CONDITION
VOLTAGE
Brake pedal: Fully released
Approximately 0V
Brake pedal: Slightly depressed
Battery voltage
PBIB1537E
BBIA0373E
Voltage: Battery voltage
PBIB0857E
P1572 ASCD BRAKE SWITCH
EC-347
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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.
6.
CHECK ASCD BRAKE SWITCH
EC-348, "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 3 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.
• Harness connectors M31, E152
• Fuse block (J/B) connector M60
• 10 A fuse (No. 20)
• 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 4.
Refer to Wiring Diagram.
3. Also check harness for short to ground and short to power.
OK or NG
OK
>> GO TO 10.
Continuity should exist.
BBIA0373E
Voltage: Battery voltage
PBIB2102E
Continuity should exist.
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