2008 INFINITI QX56 4 wheel drive

P0500 VSSEC-281
< COMPONENT DIAGNOSIS > [VK56DE]
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6. Check 1st trip DTC.
7. If 1st trip DTC is detected, go to
EC-281, "
Diagnosis Procedure".
Overall Function CheckINFOID:0000000001351657
Use this procedure to check the overall function of the vehicle speed sensor circuit. During this check, a 1st
trip DTC might not be confirmed.
WITH GST
1. Lift up drive wheels.
2. Start engine.
3. Read vehicle speed sensor signal in Service $01 with GST. The vehicle speed sensor on GST should be able to exceed 10 km/h (6 MPH) when rotating wheels with
suitable gear position.
4. If NG, go to EC-281, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000001351658
1.CHECK DTC WITH ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
Refer to BRC-24, "
CONSULT-III Function (ABS)".
OK or NG
OK >> GO TO 2.
NG >> Repair or replace.
2.CHECK COMBINATION METER FUNCTION
Refer to MWI-5
.
>> INSPECTION END
Revision: March 2010 2008 QX56

EC-340
< COMPONENT DIAGNOSIS >[VK56DE]
P1568 ICC FUNCTION
P1568 ICC FUNCTION
On Board Diagn
osis LogicINFOID:0000000001365756
•This self-diagnosis has the one trip detection logic.
• The MIL will not light up for this self-diagnosis.
NOTE:
• If DTC P1568 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC U1000,
U1001. Refer to EC-87, "
On Board Diagnosis Logic".
• If DTC P1568 is displayed with DTC U1010, first pe rform the trouble diagnosis for DTC U1010. Refer
to EC-88, "
On Board Diagnosis Logic".
• If DTC P1568 is displayed with DTC P0605, first perform the trouble diagno sis for DTC P0605. Refer
to EC-291, "
On Board Diagnosis Logic".
DTC Confirmation ProcedureINFOID:0000000001365757
CAUTION:
Always drive vehicle at a safe speed.
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:
Step 4 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-IIl
1. Turn ignition switch ON.
2. Press MAIN switch on ICC steering switch.
3. Drive the vehicle at more than 40 km/h (25 MPH).
4. Press SET/COAST switch.
5. Check DTC.
6. If DTC is detected, go to EC-340, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-lII” above.
Diagnosis ProcedureINFOID:0000000001365758
1.REPLACE ICC UNIT
1. Replace ICC unit.
2. Perform CCS-8
.
3. Check DTC of ICC unit. Refer to CCS-18
.
>> INSPECTION END
DTC No. Trouble Diagnosis
Name DTC Detecting Condit
ion Possible Cause
P1568
1568 ICC function
ECM detects a difference between signals
from ICC unit is out of specified range. • Harness or connectors
(The CAN communication line is open or
shorted.)
• ICC unit
•ECM
Revision: March 2010 2008 QX56

P1572 ICC BRAKE SWITCHEC-341
< COMPONENT DIAGNOSIS > [VK56DE]
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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

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

EC-352
< COMPONENT DIAGNOSIS >[VK56DE]
P1574 ICC VEHICLE SPEED SENSOR
P1574 ICC VEHICLE
SPEED SENSOR
Component DescriptionINFOID:0000000001528791
The ECM receives two vehicle speed signals via CAN communication 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:0000000001528792
•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-87, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DTC U1010, first pe rform the trouble diagnosis for DTC U1010. Refer
to EC-88, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DTC P0500, first perform the trouble diagno sis for DTC P0500. Refer
to EC-280, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DTC P0605, first perform the trouble diagno sis for DTC P0605. Refer
to EC-291, "
On Board Diagnosis Logic".
DTC Confirmation ProcedureINFOID:0000000001528793
CAUTION:
Always drive vehicle at a safe speed.
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:
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.
WITH CONSULT-III
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-352, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-III” above.
Diagnosis ProcedureINFOID:0000000001528794
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.
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: March 2010 2008 QX56

EC-354
< COMPONENT DIAGNOSIS >[VK56DE]
P1574 ASCD VEHICLE SPEED SENSOR
P1574 ASCD VEHICLE SPEED SENSOR
Component DescriptionINFOID:0000000001365781
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:0000000001365782
•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-87, "
DTC Confirmation Procedure" .
• If DTC P1574 is displayed with DTC U1010, first pe rform the trouble diagnosis for DTC U1010. Refer
to EC-88, "
On Board Diagnosis Logic" .
• If DTC P1574 is displayed with DTC P0500, first perform the trouble diagno sis for DTC P0500. Refer
to EC-280, "
On Board Diagnosis Logic".
• If DTC P1574 is displayed with DTC P0605, first perform the trouble diagno sis for DTC P0605. Refer
to EC-291, "
On Board Diagnosis Logic".
DTC Confirmation ProcedureINFOID:0000000001365783
CAUTION:
Always drive vehicle at a safe speed.
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:
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.
WITH CONSULT-IIl
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-354, "
Diagnosis Procedure".
WITH GST
Follow the procedure “WITH CONSULT-lII” above.
Diagnosis ProcedureINFOID:0000000001365784
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.
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: March 2010 2008 QX56

EC-426
< ECU DIAGNOSIS >[VK56DE]
ECM
ECU DIAGNOSIS
ECM
CONSULT-lll Reference Valu
e in Data Monitor ModeINFOID:0000000001351350
Remarks:
z Specification data are reference values.
z Specification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly relate d to their components signals/values/operations.
i.e. Adjust ignition timing with a timing light before monitoring IGN TIMING, because the monitor may show the specification data in spite of the
ignition timing not being adjusted to the specification data. This IGN TIMING moni tors the data calculated by the ECM according to the signals
input from the camshaft position sensor and other ignition timing related sensors.
MONITOR ITEM CONDITION SPECIFICATION
ENG SPEED • Run engine and compare CONSULT-IIl value with the tachometer indica-
tion. Almost the same speed as the
tachometer indication.
MAS A/F SE-B1 See EC-75
.
B/FUEL SCHDL See EC-75
.
A/F ALPHA-B1
A/F ALPHA-B2 See
EC-75
.
COOLAN TEMP/S • Engine: After warming up More than 70°C (158 °F)
A/F SEN1 (B1)
A/F SEN1 (B2) • Engine: After warming up Maintaining engine speed at 2,000 rpm Fluctuates around 2.2 V
HO2S2 (B1)
HO2S2 (B2) • Revving engine from idle to 3,000 rpm quickly after the following conditions
are met.
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load 0 - 0.3V ←→
Approx. 0.6 - 1.0V
HO2S2 MNTR (B1)
HO2S2 MNTR (B2) • Revving engine from idle to 3,000 rpm quickly after the following conditions
are met.
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load LEAN
←→ RICH
VHCL SPEED SE • Turn drive wheels and compare CONSULT-IIl value with the speedometer
indication. Almost the same speed as the
speedometer indication
BATTERY VOLT • Ignition switch: ON (Engine stopped) 11 - 14V
ACCEL SEN 1 • Ignition switch: ON
(Engine stopped) Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
ACCEL SEN 2*
1• Ignition switch: ON (Engine stopped) Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.2 - 4.8V
TP SEN 1-B1
TP SEN 2-B1 • Ignition switch: ON
(Engine stopped)
• Selector lever: D Accelerator pedal:
Fully released More than 0.36V
Accelerator pedal: Fully depressed Less than 4.75V
EVAP SYS PRES • Ignition switch: ON Approx. 1.8 - 4.8V
START SIGNAL • Ignition switch: ON → START → ON OFF → ON → OFF
CLSD THL POS • Ignition switch: ON
(Engine stopped) Accelerator pedal: Fully released ON
Accelerator pedal: Slightly depressed OFF
AIR COND SIG • Engine: After warming up, idle the
engine Air conditioner switch: OFF
OFF
Air conditioner switch: ON
(Compressor operates.) ON
P/N POSI SW • Ignition switch: ON Selector lever: P or N
ON
Selector lever: Except above OFF
PW/ST SIGNAL • Engine: After warming up, idle the
engine Steering wheel: Not being turned
(Forward direction)
OFF
Steering wheel: Being turned ON
Revision: March 2010 2008 QX56

EC-428
< ECU DIAGNOSIS >[VK56DE]
ECM
*1: Accelerator pedal position sensor 2 signal and throttle position sensor 2 signal are converted by ECM internally. Thus, the
y differ
from ECM terminals voltage signal.
*2: Before measuring the terminal voltage, confirm the battery is fully charged. Refer to PG-73
.
I/P PULLY SPD • Vehicle speed: More than 20 km/h (12 MPH)
Almost the same speed as the
tachometer indication
VEHICLE SPEED • Turn drive wheels and compare CONSULT-IIl value with the speedometer
indication. Almost the same speed as the
speedometer indication
TRVL AFTER MIL • Ignition switch: ON Vehicle has traveled after MIL has
turned ON.0 - 65,535 km
(0 - 40,723 mile)
A/F S1 HTR (B1)
A/F S1 HTR (B2) • Engine: After warming up, idle the engine
4 - 100%
AC PRESS SEN • Engine: Idle
• Both A/C switch and blower fan switch: ON (Compressor operates.)
1.0 - 4.0V
VHCL SPEED SE • Turn drive wheels and compare CONSULT-IIl value with the speedometer
indication. Almost the same speed as the
speedometer indication
SET VHCL SPD • Engine: Running ASCD: Operating.The preset vehicle speed is dis-
played.
MAIN SW • Ignition switch: ON MAIN switch: Pressed
ON
MAIN switch: Released OFF
CANCEL SW • Ignition switch: ON CANCEL switch: Pressed
ON
CANCEL switch: Released OFF
RESUME/ACC SW • Ignition switch: ON RESUME/ACCELERATE switch:
Pressed
ON
RESUME/ACCELERATE switch: Re-
leased OFF
SET SW • Ignition switch: ON SET/COAST switch: Pressed
ON
SET/COAST switch: Released OFF
DIST SW • Ignition switch: ON DISTANCE switch: Pressed
ON
DISTANCE switch: Released OFF
BRAKE SW1 • Ignition switch: ON Brake pedal: Fully released
ON
Brake pedal: Slightly depressed OFF
BRAKE SW2 • Ignition switch: ON Brake pedal: Fully released
OFF
Brake pedal: Slightly depressed ON
CRUISE LAMP • Ignition switch: ON MAIN switch: Pressed at the 1st time
→ at the 2nd timeON
→ OFF
SET LAMP • MAIN switch: ON
• Vehicle speed: Between 40 km/h
(25 MPH) and 144 km/h (89
MPH) ASCD: Operating
ON
ASCD: Not operating OFF
ALT DUTY • Engine: Idle 0 - 80%
BAT CUR SEN • Engine speed: Idle
• Battery: Fully charged*
2
• Selector lever: P or N
• Air conditioner switch: OFF
•No load Approx. 2,600 - 3,500mV
ALT DUTY SIG • Power generation voltage variable control: Operating
ON
• Power generation voltage variable control: Not operating OFF
MONITOR ITEM
CONDITION SPECIFICATION
Revision: March 2010 2008 QX56