2008 INFINITI QX56 Stop light

EC-106
< COMPONENT DIAGNOSIS >[VK56DE]
P0101 MAF SENSOR
P0101 MAF SENSOR
Component DescriptionINFOID:0000000001351401
The mass air flow sensor is placed in the stream of intake air. It mea-
sures the intake flow rate by measuring a part of the entire intake
flow. The mass air flow sensor c
ontrols the temperature of the hot
wire to a certain amount. The heat generated by the hot wire is
reduced as the intake air flows around it. The more air, the greater
the heat loss.
Therefore, the electric current supplied to the hot wire is changed to
maintain the temperature of the hot wire as air flow increases. The
ECM detects the air flow by means of this current change.
On Board Diagn osis LogicINFOID:0000000001351403
DTC Confirmation ProcedureINFOID:0000000001351404
Perform PROCEDURE FOR MALFUNCTION A first.
If the DTC cannot be confirmed, perform PROCEDURE FOR MALFUNCTION B.
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 A
NOTE:
If engine will not start or stops soon, wait at leas t 10 seconds with engine stopped (Ignition switch ON) instead
of running engine at idle speed.
With CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Run engine for at least 10 seconds at idle speed.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-109, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
PROCEDURE FOR MALFUNCTION B
NOTE:
Check vehicle specifications and VIN, then select the procedure to be performed. (Refer to the table below.)
BBIA0355E
DTC No. Trouble diagnosis name DTC detecting conditionPossible cause
P0101
0101 Mass air flow sensor circuit
range/performance A)
A high voltage from the sensor is sent to ECM
under light load driving condition. • Harness or connectors
(The sensor circuit is open or
shorted.)
• Mass air flow sensor
• EVAP control system pressure sensor
• Intake air temperature sensor
B) A low voltage from the sensor is sent to ECM
under heavy load driving condition. • Harness or connectors
(The sensor circuit is open or
shorted.)
• Intake air leaks
• Mass air flow sensor
• EVAP control system pressure sensor
• Intake air temperature sensor
Revision: March 2010 2008 QX56

P0441 EVAP CONTROL SYSTEMEC-221
< COMPONENT DIAGNOSIS > [VK56DE]
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With CONSULT-III
1. Disconnect vacuum hose connected to EVAP canister purge volume control solenoid valve at EVAP ser-
vice port and install vacuum gauge. For the location of EVAP service port, refer to EC-37, "
Description".
2. Start engine and let it idle.
3. Select “PURG VOL CONT/V” in “ACTIVE TEST” mode with CONSULT-III.
4. Rev engine up to 2,000 rpm.
5. Touch “Qd” and “Qu” on CONSULT-III screen to adjust “PURG VOL CONT/V” opening and check vacuum
existence.
OK or NG
OK >> GO TO 7.
NG >> GO TO 4.
3.CHECK PURGE FLOW
Without CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Stop engine.
3. Disconnect vacuum hose connected to EVAP canister purge volume control solenoid valve at EVAP ser-
vice port and install vacuum gauge. For the location of EVAP service port, refer to EC-37, "
Description".
4. Start engine and let it idle.
Do not depress accelerator pedal even slightly.
5. Check vacuum gauge indication before 60 seconds passed after starting engine.
6. Revving engine up to 2,000 rpm after 100 seconds passed after starting engine.
OK or NG
OK >> GO TO 7.
NG >> GO TO 4.
4.CHECK EVAP PURGE LINE
1. Turn ignition switch OFF.
2. Check EVAP purge line for improper connection or disconnection. Refer to EC-37, "
Description".
OK or NG
OK >> GO TO 5.
NG >> Repair it.
5.CHECK EVAP PURGE HOSE AND PURGE PORT
1. Disconnect purge hoses connect ed to EVAP service port A and
EVAP canister purge volume control solenoid valve B.
2. Blow air into each hose and EVAP purge port C.
PURG VOL CONT/V Vacuum
100% Should exist.
0% Should not exist.
Vacuum should not exist.
Vacuum should exist.
SEF367U
Revision: March 2010 2008 QX56

P0643 SENSOR POWER SUPPLYEC-293
< COMPONENT DIAGNOSIS > [VK56DE]
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P0643 SENSOR POWER SUPPLY
On Board Diagnosis LogicINFOID:0000000001351684
This self-diagnosis has the on
e trip detection logic.
FA I L - S A F E M O D E
When the malfunction is detected, ECM ent ers fail-safe mode and the MIL lights up.
DTC Confirmation ProcedureINFOID:0000000001351685
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.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 10V at idle.
WITH CONSULT-III
1. Start engine and let it idle for 1 second.
2. Check DTC.
3. If DTC is detected, go to EC-293, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001351687
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-86, "
Ground Inspection".
OK or NG
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0643
0643 Sensor power supply circuit
short ECM detects a voltage of power source
for sensor is excessively low or high. • Harness or connectors
(APP sensor 1 circuit is shorted.)
(PSP sensor circuit is shorted.)
(Battery current sensor circuit is shorted.)
(Refrigerant pressure se nsor circuit is short-
ed.)
(EVAP control system pressure sensor circuit
is shorted.)
• Accelerator pedal position sensor
• Power steering pressure sensor
• Refrigerant pressure sensor
• EVAP control system pressure sensor
Engine operation condition in fail-safe mode
ECM stops the electric throttle control actuator control, throttle valve is maintained at a fixed opening (approx. 5 degrees) b y the return
spring.
BBIA0354E
Revision: March 2010 2008 QX56

P1572 ICC BRAKE SWITCHEC-341
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P1572 ICC BRAKE SWITCH
Component DescriptionINFOID:0000000001365766
When the brake pedal is depressed, ICC 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
CCS-13
for the ICC function.
On Board Diagnosis LogicINFOID:0000000001365768
•This diagnosis has the on e trip detection logic.
• The MIL will not light up for this self-diagnosis.
NOTE:
• If DTC P1572 is displayed with DT C P0605, first perform the trouble diagnosis for DTC P0605. Refer
to EC-291, "
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 ma lfunction A is detected in two
consecutive trips, DTC is not stored in ECM memory.
DTC Confirmation ProcedureINFOID:0000000001365769
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
• If DTC Confirmation Procedure has been previously conduc ted, 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 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.
WITH CONSULT-IIl
1. Start engine (VDC switch OFF).
2. Select “DATA MONITOR” mode with CONSULT-IIl.
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.
BBIA0470E
DTC No.Trouble diagnosis
name DTC detecting condition
Possible cause
P1572
1572 ICC brake switch A)
When vehicle speed is above 30 km/h (19
MPH), 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
driving
Revision: March 2010
2008 QX56

EC-346
< COMPONENT DIAGNOSIS >[VK56DE]
P1572 ICC BRAKE SWITCH
Component Inspection
INFOID:0000000001365772
ICC BRAKE SWITCH
1. Turn ignition switch OFF.
2. Disconnect ICC brake switch harness connector.
3. Check continuity between ICC brake switch terminals 1 and 2 under the following conditions.
If NG, adjust ICC brake switch installation, refer to BR-15,
"Inspection and Adjustment", and perform step 3 again.
STOP LAMP SWITCH
1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.
3. Check continuity between stop lamp switch terminals 3 and 4under the following conditions.
If NG, adjust stop lamp switch installation, refer to BR-15,
"Inspection and Adjustment", and perform step 3 again.
ICC BRAKE HOLD RELAY
1. Apply 12V direct current between ICC brake hold relay terminals 1 and 2.
2. Check continuity between relay terminals 3 and 4, 6 and 7 under
the following conditions.
3. If NG, replace ICC brake hold relay.
Condition Continuity
Brake pedal: Fully released. Should exist.
Brake pedal: Slightly depressed. Should not exist.
PBIB1536E
ConditionContinuity
Brake pedal: Fully released. Should not exist.
Brake pedal: Slightly depressed. Should exist.
PBIB2103E
ConditionBetween terminals Continuity
12V direct current supply
between terminals 1 and 2 3 and 4
Should not exist
6 and 7 Should exist
No current supply 3 and 4
Should exist
6 and 7 Should not exist
MBIB0063E
Revision: March 2010 2008 QX56

P1572 ASCD BRAKE SWITCHEC-347
< COMPONENT DIAGNOSIS > [VK56DE]
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P1572 ASCD BRAKE SWITCH
Component DescriptionINFOID:0000000001528784
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 Diagnosis LogicINFOID:0000000001528786
•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-291, "
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 ma lfunction A is detected in two
consecutive trips, DTC is not stored in ECM memory.
DTC Confirmation ProcedureINFOID:0000000001528787
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
• If DTC Confirmation Procedure has been previously conduc ted, 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 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.
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.
4. 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: March 2010
2008 QX56

P1572 ASCD BRAKE SWITCHEC-351
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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-351, "
Component Inspection".
OK or NG
OK >> GO TO 11.
NG >> Replace stop lamp switch.
11 .CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000001528790
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,
"Inspection and Adjustment", 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,
"Inspection and Adjustment", and perform step 3 again.
Continuity should exist.
Condition
Continuity
Brake pedal: Fully released Should exist.
Brake pedal: Slightly depressed Should not exist.
SEC023D
ConditionContinuity
Brake pedal: Fully released Should not exist.
Brake pedal: Slightly depressed Should exist.
PBIB2103E
Revision: March 2010 2008 QX56

EC-356
< COMPONENT DIAGNOSIS >[VK56DE]
P1805 BRAKE SWITCH
P1805 BRAKE SWITCH
DescriptionINFOID:0000000001528795
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 Diagn
osis LogicINFOID:0000000001528797
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:0000000001528798
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-356, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001528800
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 SWIT CH 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 pedalStop lamp
Fully released Not illuminated
Slightly depressed Illuminated
Revision: March 2010 2008 QX56