2010 INFINITI QX56 ecm

EC-342
< COMPONENT DIAGNOSIS >[VK56DE]
P1572 ICC BRAKE SWITCH
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 101 and stop lamp switch terminal 4.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
5. Check harness continuity between ECM terminal 101 and ICC hold relay terminal 6. Refer to Wiring Diagram.
6. Also check harness for short to ground and short to power.
7. Disconnect ICC unit harness connector.
8. Check harness continuity between ECM terminal 101 and ICC unit terminal 38. Refer to Wiring Diagram.
9. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 13.
NG >> GO TO 12.
12.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors E34, B40
• Harness for open or short between ICC unit and ECM
• Harness for open or short between ECM and ICC brake hold relay
• Harness for open or short between ECM and ICC brake switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
13.CHECK STOP LAMP SWITCH
Refer to EC-343, "
Component Inspection".
OK or NG
OK >> GO TO 14.
NG >> Replace stop lamp switch.
14.CHECK ICC BRAKE HOLD RELAY POWER SUPPLY AND GROUND CIRCUIT FOR OPEN AND
SHORT
1. Check harness continuity between ICC brake hold re lay terminal 1 and ICC unit terminal 47, ICC brake
hold relay terminal 2 and ground.
Refer to Wiring Diagram
2. Also check harness for short to ground or short to power in harness or connectors.
OK or NG
OK >> GO TO 15.
NG >> Repair or replace.
15.CHECK ICC BRAKE HOLD RELAY
Refer to EC-343, "
Component Inspection".
OK >> GO TO 16.
NG >> Replace ICC brake hold relay.
16.CHECK INTERMITTENT INCIDENT Continuity should exist.
Continuity should exist.
Continuity should exist.
Continuity should exist
Revision: April 20092010 QX56

EC-344
< COMPONENT DIAGNOSIS >[VK56DE]
P1572 ASCD BRAKE SWITCH
P1572 ASCD BRAKE SWITCH
Component DescriptionINFOID: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).
Refer to
EC-33, "
System Description" for the ASCD function.
On Board Diagn osis LogicINFOID: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 pe rform the trouble diagnosis for DTC P0605. Refer
to EC-286, "
On Board Diagnosis Logic".
• This self-diagnosis has the one tr ip 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 ma lfunction A is detected in two
consecutive trips, DTC is not stored in ECM memory.
DTC Confirmation ProcedureINFOID: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 li fted 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
Revision: April 20092010 QX56

P1572 ASCD BRAKE SWITCHEC-345
< COMPONENT DIAGNOSIS > [VK56DE]
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O4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to
EC-345, "
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-345, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID: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
CONDITIONVOLTAGE
Brake pedal: Slightly depressed Approximately 0V
Brake pedal: Fully released Battery voltage
MBIB0061E
CONDITIONINDICATION
Brake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
Revision: April 20092010 QX56

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
Revision: April 20092010 QX56

P1572 ASCD BRAKE SWITCHEC-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
Refer to EC-348, "
Component Inspection".
OK or NG
OK >> GO TO 11.
NG >> Replace ASCD brake switch.
7.CHECK STOP LAMP SWIT CH 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 SI GNAL 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.
Revision: April 20092010 QX56

P1574 ICC VEHICLE SPEED SENSOR
EC-349
< COMPONENT DIAGNOSIS > [VK56DE]
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P1574 ICC VEHICLE SPEED SENSOR
Component DescriptionINFOID:0000000005149409
The ECM receives two vehicle speed signals via CAN comm
unication line. One is sent from “unified meter and
A/C amp.”, and the other is from TCM (Transmission control module). The ECM uses these signals for ICC
control. Refer to CCS-13
for ICC functions.
On Board Diagnosis LogicINFOID:0000000005149410
•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 UXXXX, first perform the tr ouble diagnosis for DTC UXXXX.
• If DTC P1574 is displayed with DT C P0500, first perform the trouble diagnosis for DTC P0500. Refer
to EC-275, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DT C P0605, first perform the trouble diagnosis for DTC P0605. Refer
to EC-286, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DT C P0607, first perform the trouble diagnosis for DTC P0607. Refer
to EC-288, "
On Board Diagnosis Logic".
DTC Confirmation ProcedureINFOID:0000000005149411
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
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:
Step 3 may be conducted with the dr ive 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.
2. Drive the vehicle at more than 40 km/h (25MPH).
3. Check 1st trip DTC.
4. If DTC is detected, go to EC-349, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149412
1.CHECK DTC WITH TCM
Check DTC with TCM. Refer to TM-30, "
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)”
Refer to BRC-23, "
CONSULT-III Function (ABS)".
OK or NG
DTC No. Trouble Diagnosis Name DTC Detecting Condition Possible Cause
P1574
1574 ICC 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
Revision: April 20092010 QX56

P1574 ASCD VEHICLE SPEED SENSOREC-351
< COMPONENT DIAGNOSIS > [VK56DE]
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P1574 ASCD VEHICLE SPEED SENSOR
Component DescriptionINFOID:0000000005149413
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-33, "
System Description" for ASCD functions.
On Board Diagnosis LogicINFOID:0000000005149414
• 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 UXXXX, first perform the tr ouble diagnosis for DTC UXXXX.
• If DTC P1574 is displayed with DT C P0500, first perform the trouble diagnosis for DTC P0500. Refer
to EC-275, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DT C P0605, first perform the trouble diagnosis for DTC P0605. Refer
to EC-286, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DT C P0607, first perform the trouble diagnosis for DTC P0607. Refer
to EC-288, "
On Board Diagnosis Logic".
DTC Confirmation ProcedureINFOID:0000000005149415
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
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:
Step 3 may be conducted with the dr ive 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-351, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149416
1.CHECK DTC WITH TCM
Check DTC with TCM. Refer to TM-30, "
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)
Refer to BRC-23, "
CONSULT-III Function (ABS)".
DTC No. Trouble Diagnosis
Name DTC Detecting Condit
ion 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
Revision: April 20092010 QX56

P1805 BRAKE SWITCHEC-353
< COMPONENT DIAGNOSIS > [VK56DE]
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P1805 BRAKE SWITCH
DescriptionINFOID:0000000005149417
Brake switch signal is applied to the ECM through t
he 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 LogicINFOID:0000000005149418
The MIL will not light up for this self-diagnosis.
FA I L - S A F E M O D E
When the malfunction is detected, the ECM enters fail-safe mode.
DTC Confirmation ProcedureINFOID:0000000005149419
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-353, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149420
1.CHECK OVERALL FUNCTION-II
With CONSULT-III
Check “BRAKE SW2” indication in “DATA MONITOR” mode.
Without CONSULT-III
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
CONDITIONINDICATION
Brake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
Revision: April 20092010 QX56