2010 INFINITI QX56 brake

ENGINE CONTROL SYSTEMEC-25
< FUNCTION DIAGNOSIS > [VK56DE]
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1. EVAP canister purge volume control
solenoid valve (view with engine
cover removed) 2. EVAP service port (view with engine
cover removed) 3. Crankshaft position sensor (POS)
(view from under the vehicle)
4. Engine oil pan (view from under the vehicle) 5. Condenser-1
6. Brake fluid reservoir
7. EVAP canister (view with fuel tank removed) 8. EVAP control system pressure sen-
sor (view with fuel tank removed) 9. EVAP canister vent control valve
(view with fuel tank removed)
10. Rear suspension member (view with fuel tank removed) 11. Refrigerant pressure sensor (view
with front grille removed) 12. Intake valve timing control position
sensor (bank 2) (view with engine
cover and intake air duct removed)
13. Intake valve timing control position sensor (bank 1) (view with engine
cover and intake air duct removed) 14. Intake valve timing control solenoid
valve (bank 2) (view with engine cov-
er and intake air duct removed) 15. Drive belt (view with engine cover
and intake air duct removed)
16. Radiator hose (view with engine cov- er and intake air duct removed) 17. Intake valve timing control solenoid
valve (bank 1) (view with engine cov-
er and intake air duct removed)
: Vehicle front
BBIA0774E
Revision: April 20092010 QX56

AUTOMATIC SPEED CONTROL DEVICE (ASCD)EC-33
< FUNCTION DIAGNOSIS > [VK56DE]
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
System DescriptionINFOID:0000000005149068
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line
BASIC ASCD SYSTEM
Refer to Owner's Manual for ASCD operating instructions.
Automatic Speed Control Device (ASCD) allows a driver to keep vehicle at predetermined constant speed
without depressing accelerator pedal. Driver can set
vehicle speed in advance between approximately 40 km/
h (25 MPH) and 144 km/h (89 MPH).
ECM controls throttle angle of electric thro ttle control actuator to regulate engine speed.
Operation status of ASCD is indicated by CRUISE i ndicator and SET indicator in combination meter. If any
malfunction occurs in ASCD system, it automatically deactivates control.
NOTE:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.
SET OPERATION
Press MAIN switch. (The CRUISE indicato r in combination meter illuminates.)
When vehicle speed reaches a desired speed between approximately 40 km/h (25 MPH) and 144 km/h (89
MPH), press SET/COAST switch. (Then SET indicator in combination meter illuminates.)
ACCELERATE OPERATION
If the RESUME/ACCELERATE switch is pressed during cr uise control driving, increase the vehicle speed until
the switch is released or vehicle speed reac hes maximum speed controlled by the system.
And then ASCD will keep the new set speed.
CANCEL OPERATION
When any of following conditions exis t, cruise operation will be canceled.
• CANCEL switch is pressed
• More than 2 switches at ASCD steer ing switch are pressed at the same time (Set speed will be cleared)
• Brake pedal is depressed
• Selector lever is changed to N, P, R position
• Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed
• VDC system is operated
When the ECM detects any of the following conditions, the ECM will cancel the cruise operation and inform
the driver by blinking indicator lamp.
• Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE indicator may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE indicator will
stop blinking and the cruise operation will be able to work by pressing SET/COAST switch or RESUME/
ACCELERATE switch.
• Malfunction for some self-diagnoses regarding ASCD control: SET indicator will blink quickly.
If MAIN switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.
COAST OPERATION
When the SET/COAST switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will keep the new set speed.
RESUME OPERATION
Sensor Input signal to ECM ECM functionActuator
ASCD brake switch Brake pedal operation
ASCD vehicle speed controlElectric throttle control
actuator
Stop lamp switch
Brake pedal operation
ASCD steering switch ASCD steering switch operation
Wheel sensor Vehicle speed*
TCM Gear position
Powertrain revolution*
Revision: April 20092010 QX56

EC-34
< FUNCTION DIAGNOSIS >[VK56DE]
AUTOMATIC SPEED CONTROL DEVICE (ASCD)
When the RESUME/ACCELERATE
switch is pressed after cancel operation other than pressing MAIN switch
is performed, vehicle speed will return to last set s peed. To resume vehicle set speed, vehicle condition must
meet following conditions.
• Brake pedal is released
• A/T selector lever is in other than P and N positions
• Vehicle speed is greater than 40 km/h (25 MPH) and less than 144 km/h (89 MPH)
Component DescriptionINFOID:0000000005149069
ASCD STEERING SWITCH
Refer to EC-332.
ASCD BRAKE SWITCH
Refer to EC-344, and EC-388.
STOP LAMP SWITCH
Refer to EC-344, EC-353 and EC-388.
ELECTRIC THROTTLE CONTROL ACTUATOR
Refer to EC-356, EC-359, EC-363 and EC-365.
ASCD INDICATOR
Refer to EC-391.
Revision: April 20092010 QX56

EC-64
< FUNCTION DIAGNOSIS >[VK56DE]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
ItemDIAGNOSTIC TEST MODE
WORK SUP-
PORT SELF-DIAGNOSTIC
RESULTS DATA
MONI-
TOR ACTIVE
TEST DTC & SRT
CONFIRMATION
DTC*1 FREEZE
FRAME
DATA*2 SRT
STATUS DTC
WORK
SUP-
PORT
ENGINE CONTROL COMPONENT PARTS
INPUT
Crankshaft position sensor (POS) ×××
Camshaft position sensor (PHASE) ×××
Mass air flow sensor ××
Engine coolant temperature sensor ××××
Air fuel ratio (A/F) sensor 1 ××× ×
Heated oxygen sensor 2 ××× ×
Wheel sensor ×××
Accelerator pedal position sensor ××
Throttle position sensor ×××
Fuel tank temperature sensor ×××
EVAP control system pressure sen-
sor ××
Intake air temperature sensor ×××
Knock sensor ×
Refrigerant pressure sensor ×
Closed throttle position switch (ac-
celerator pedal position sensor sig-
nal) ×
Air conditioner switch ×
Park/neutral position (PNP) signal ××
Stop lamp switch ××
Power steering pressure sensor ××
Battery voltage ×
Load signal ×
Intake valve timing control position
sensor ××
Fuel level sensor ××
Battery current sensor ××
ICC steering switch ××
ASCD steering switch ××
ICC brake switch ××
ASCD brake switch ××
Revision: April 20092010 QX56

EC-68
< FUNCTION DIAGNOSIS >[VK56DE]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
TP SEN 1-B1 [V]
××
• The throttle position sensor signal volt-
age is displayed. • TP SEN 2-B1 signal is converted by
ECM internally. Thus, it differs from
ECM terminal voltage signal.
TP SEN 2-B1 [V]
××
FUEL T/TMP SE
[ ° C] or [ °F] • The fuel temperature (determined by the
signal voltage of the fuel tank tempera-
ture sensor) is displayed.
INT/A TEMP SE
[ ° C] or [ °F] ×× • The intake air temperature (determined
by the signal voltage of the intake air
temperature sensor) is indicated.
EVAP SYS PRES
[V] • The signal voltage of EVAP control sys-
tem pressure sensor is displayed.
FUEL LEVEL SE [V] ו The signal voltage of the fuel level sen-
sor is displayed.
START SIGNAL
[ON/OFF] • Indicates start signal status [ON/OFF]
computed by the ECM according to the
signals of engine speed and battery volt-
age. • After starting the engine, [OFF] is dis-
played regardless of the starter signal.
CLSD THL POS
[ON/OFF] ×ו Indicates idle position [ON/OFF] comput-
ed by ECM according to the accelerator
pedal position sensor signal.
AIR COND SIG
[ON/OFF] ×ו Indicates [ON/OFF] condition of the air
conditioner switch as determined by the
air conditioner signal.
P/N POSI SW
[ON/OFF] ××
• Indicates [ON/OFF] condition from the
park/neutral position (PNP) signal.
PW/ST SIGNAL
[ON/OFF] ×ו [ON/OFF] condition of the power steering
system (determined by the signal voltage
of the power steering pressure sensor
signal) is indicated.
LOAD SIGNAL [ON/
OFF] ×ו Indicates [ON/OFF] condition from the
electrical load signal.
ON: Rear window defogger switch is ON
and/or lighting switch is in 2nd position.
OFF: Both rear window defogger switch
and lighting switch are OFF.
IGNITION SW
[ON/OFF] ×ו Indicates [ON/OFF] condition from igni-
tion switch signal.
HEATER FAN SW
[ON/OFF] ×
• Indicates [ON/OFF] condition from heat-
er fan switch signal.
BRAKE SW
[ON/OFF] • Indicates [ON/OFF] condition from the
stop lamp switch signal.
INJ PULSE-B1
[msec] • Indicates the actual fuel injection pulse
width compensated by ECM according to
the input signals. • When the engine is stopped, a certain
computed value is indicated.
INJ PULSE-B2
[msec]
IGN TIMING [BT-
DC] • Indicates the ignition timing computed by
ECM according to the input signals. • When the engine is stopped, a certain
value is indicated.
CAL/LD VALUE [%] • “Calculated load value” indicates the val-
ue of th

e current air flow divided by peak
air flow.
MASS AIRFLOW
[g·m/s] • Indicates the mass air flow computed by
ECM according to the signal voltage of
the mass air flow sensor.
Monitored item
[Unit] ECM IN-
PUT SIG-
NALS MAIN
SIGNALS Description
Remarks
Revision: April 20092010 QX56

EC-70
< FUNCTION DIAGNOSIS >[VK56DE]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
ACTIVE TEST MODE
Test Item
A/F S1 HTR (B1)
[%]• A/F sensor 1 heater control value com-
puted by ECM according to the input sig-
nals.
• The current flow to the heater becomes larger as the value increases.
A/F S1 HTR (B2)
[%]
AC PRESS SEN [V]
• The signal voltage from the refrigerant
pressure sensor is displayed.
VHCL SPEED SE
[km/h] or [mph] • The vehicle speed computed from the
vehicle speed signal sent from combina-
tion meter is displayed.
SET VHCL SPD
[km/h] or [mph] • The preset vehicle speed is displayed.
MAIN SW
[ON/OFF] • Indicates [ON/OFF] condition from MAIN
switch signal.
CANCEL SW
[ON/OFF] • Indicates [ON/OFF] condition from CAN-
CEL switch signal.
RESUME/ACC SW
[ON/OFF] • Indicates [ON/OFF] condition from RE-
SUME/ACCELERATE switch signal.
SET SW
[ON/OFF] • Indicates [ON/OFF] condition from SET/
COAST switch signal.
BRAKE SW1
[ON/OFF] • Indicates [ON/OFF] condition from
ASCD brake switch signal.
BRAKE SW2
[ON/OFF] • Indicates [ON/OFF] condition of stop
lamp switch signal.
DIST SW
[ON/OFF] • Indicates [ON/OFF] condition from DIS-
TANCE switch signal.
ALT DUTY [%] • Indicates the duty ratio of the power gen-
eration command value. The ratio is cal-
culated by ECM based on the battery
current sensor signal.
BAT CUR SEN [mV] • The signal voltage of battery current sen-
sor is displayed.
ALT DUTY SIG
[ON/OFF] • The control condition of the power gener-
ation voltage variable control (deter-
mined by ECM according to the input
signals) is indicated.
ON: Power generation voltage variable
control is active.
OFF: Power generation voltage variable
control is inactive.
A/F ADJ-B1 • Indicates the correction factor stored in
ECM. The factor is calculated from the
difference between the target air/fuel ra-
tio stored in ECM and the air-fuel ratio
calculated from air fuel ratio (A/F) sensor
1 signal.
A/F ADJ-B2 Monitored item
[Unit] ECM IN-
PUT SIG-
NALS MAIN
SIGNALS Description
Remarks
Revision: April 20092010 QX56

EC-138
< COMPONENT DIAGNOSIS >[VK56DE]
P0130, P0150 A/F SENSOR 1
PROCEDURE FOR MALFUNCTION B
CAUTION:
Always drive vehicle at a safe speed.
With CONSULT-III
1. Start engine and warm it up to normal operating temperature.
2. Select “A/F SEN1 (B1)” or “A/F SEN1 (B
2)” in “DATA MONITOR” mode with CONSULT-III.
3. Check “A/F SEN1 (B1)” or “A/F SEN1 (B2)” indication.
If the indication is constantly approx. 2.2 V and does not fluctuates, go to EC-138, "
Diagnosis Procedure".
If the indication fluctuates around 2.2 V, go to next step.
4. Select “A/F SEN1 (B1) P1276” (for DTC P0130) or “A/F SEN1 (B2) P1286” (for DTC P0150) of “A/F
SEN1” in “DTC WORK SUPPORT” mode with CONSULT-III.
5. Touch “START”.
6. When the following conditions are met, “TESTING” will be displayed on the CONSULT-III screen.
If “TESTING” is not displayed after 20 seconds, retry from step 2.
7. Release accelerator pedal fully. NOTE:
Never apply brake during releasing the accelerator pedal.
8. Make sure that “TESTING” changes to “COMPLETED”. If “TESTING” changed to “OUT OF CONDITION”, retry from step 6.
9. Make sure that “OK” is display ed after touching “SELF-DIAG RESULT”.
If “NG” is displayed, go to EC-138, "
Diagnosis Procedure".
Overall Function CheckINFOID:0000000005149158
PROCEDURE FOR MALFUNCTION B
Use this procedure to check the overall function of the A/F sensor 1 circuit. During this check, a 1st trip DTC
might not be confirmed.
With GST
1. Start engine and warm it up to normal operating temperature.
2. Drive the vehicle at a speed of 80 km/h (50 MPH) for a few minutes in the suitable gear position.
3. Set shift lever to D position, then release the acce lerator pedal fully until the vehicle speed decreases to
50 km/h (30 MPH).
NOTE:
Never apply brake during releasing the accelerator pedal.
4. Repeat steps 2 and 3 for five times.
5. Stop the vehicle and turn ignition switch OFF.
6. Wait at least 10 seconds and restart engine.
7. Repeat steps 2 and 3 for five times.
8. Stop the vehicle and connect GST to the vehicle.
9. Make sure that no 1st trip DTC is displayed.
If the 1st trip DTC is displayed, go to EC-138, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149159
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
ENG SPEED 850 - 3,200 rpm
VHCL SPEED SE More than 64 km/h (40 MPH)
B/FUEL SCHDL 1.0 - 8.0 msec
Shift lever D position
Revision: April 20092010 QX56

P1572 ICC BRAKE SWITCHEC-337
< COMPONENT DIAGNOSIS > [VK56DE]
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P1572 ICC BRAKE SWITCH
Component DescriptionINFOID:0000000005149399
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:0000000005149400
•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-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 ma lfunction A is detected in two
consecutive trips, DTC is not stored in ECM memory.
DTC Confirmation ProcedureINFOID:0000000005149401
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 lamp lights up.
3. 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: April 20092010 QX56