2009 INFINITI QX56 ECO mode

P0461 FUEL LEVEL SENSOREC-267
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P0461 FUEL LEVEL SENSOR
Component DescriptionINFOID:0000000003771533
The fuel level sensor is mounted in the fuel level sensor unit. The
sensor detects a fuel level in the fuel tank and transmits a signal to
the combination meter. The combination meter sends the fuel level
sensor signal to the ECM through CAN communication line.
It consists of two parts, one is mechanical float and the other is vari-
able resistor. Fuel level sensor output voltage changes depending on
the movement of the fuel mechanical float.
On Board Diagnosis LogicINFOID:0000000003771534
NOTE:

If DTC P0461 is displayed with DTC U1000 or U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-86
.
 If DTC P0461 is displayed with DT C P0607, first perform the trouble diagnosis for DTC P0607. Refer
to EC-284
.
Driving long distances naturally affect fuel gauge level.
This diagnosis detects the fuel gauge malfunction of the gauge not moving even after a long distance has
been driven.
Overall Function CheckINFOID:0000000003771535
Use this procedure to check the overall function of the f uel level sensor function. During this check, a 1st trip
DTC might not be confirmed.
WARNING:
When performing following procedure, be sure to observe the handling of the fuel. Refer to FL-11,
"Removal and Installation".
TESTING CONDITION:
Before starting overall function check, preparation of draining fuel and refilling fuel is required.
WITH CONSULT-III
NOTE:
Start from step 10, if it is possible to confirm that the fuel cannot be drained by 30 (7-7/8 US gal, 6-5/
8 Imp gal) in advance.
1. Prepare a fuel container and a spare hose.
2. Release fuel pressure from fuel line, refer to EC-487, "Fuel Pressure Check"
.
3. Remove the fuel feed hose on the fuel level sensor unit.
4. Connect a spare fuel hose where the fuel feed hose was removed.
5. Turn ignition switch OFF and wait at least 10 seconds then turn ON.
6. Select “FUEL LEVEL SE” in “DAT A MONITOR” mode with CONSULT-III.
7. Check “FUEL LEVEL SE” output voltage and note it.
8. Select “FUEL PUMP” in “ACT IVE TEST” mode with CONSULT-III.
9. Touch “ON” and drain fuel approximately 30 (7-7/8 US gal, 6-5/8 Imp gal) and stop it.
10. Check “FUEL LEVEL SE” output voltage and note it.
11. Fill fuel into the fuel tank for 30 (7-7/8 US gal, 6-5/8 Imp gal).
BBIA0402E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0461
0461 Fuel level sensor circuit
range/performance The output signal of the fuel level sensor does
not change within the specified range even
though the vehicle has been driven a long dis-
tance.  Harness or connectors
(The CAN communication line is open or
shorted)
 Harness or connectors
(The sensor circuit is open or shorted)
 Combination meter
 Fuel level sensor
Revision: December 20092009 QX56

P0500 VSSEC-271
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P0500 VSS
DescriptionINFOID:0000000003771541
NOTE:

If DTC P0500 is displayed with DTC U1000 or U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-86
.
 If DTC P0500 is displayed with DT C P0607, first perform the trouble diagnosis for DTC P0607. Refer
to EC-284
.
The vehicle speed signal is sent to the combination me ter from the “ABS actuator and electric unit (control
unit)” by CAN communication line. The c combination meter then sends a signal to the ECM by CAN commu-
nication line.
On Board Diagnosis LogicINFOID:0000000003771542
FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode.
DTC Confirmation ProcedureINFOID:0000000003771543
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:
Steps 1 and 2 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. Read “VHCL SPEED SE” in “DATA MONITOR” m ode with CONSULT-III. The vehicle speed on CON-
SULT-III should exceed 10 km/h (6 MPH) when rotating wheels with suitable gear position.
If NG, go to EC-272, "Diagnosis Procedure"
.
If OK, go to following step.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Warm engine up to normal operating temperature.
5. Maintain the following conditions for at least 60 consecutive seconds.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0500
0500 Vehicle speed sensor The vehicle speed signal sent to ECM is
almost 0 km/h (0 MPH) even when vehicle
is being driven.  Harness or connectors
(The CAN communication line is open or short-
ed)
 Harness or connectors (The vehicle speed signal circuit is open or
shorted)
 Wheel sensor
 Combination meter
 ABS actuator and electric unit (control unit)
Detected items Engine operating condition in fail-safe mode
Vehicle speed sensor When the fail-safe system for vehicle speed sensor is activated, the cooling fan operates (High) while
engine is running.
ENG SPEED 1,600 - 6,000 rpm
COOLAN TEMP/S More than 70
°C (158 °F)
Revision: December 20092009 QX56

EC-282
< COMPONENT DIAGNOSIS >[VK56DE]
P0605 ECM
P0605 ECM
Component DescriptionINFOID:0000000003771563
The ECM consists of a microcomputer and connectors for signal
input and output and for power supply. The ECM controls the engine.
On Board Diagn
osis LogicINFOID:0000000003771564
This self-diagnosis has one or two trip detection logic.
FAIL-SAFE MODE
ECM enters fail-safe mode when the malfunction A is detected.
DTC Confirmation ProcedureINFOID:0000000003771565
Perform PROCEDURE FOR MALFUNCTION A first. If th e 1st trip DTC cannot be confirmed, perform
PROCEDURE FOR MALFUNCTION B. If there is no malfunction on PROCEDURE FOR MALFUNCTION
B, perform PROCEDURE FOR MALFUNCTION C.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
PROCEDURE FOR MALFUNCTION A
1. Turn ignition switch ON.
2. Check 1st trip DTC.
3. If 1st trip DTC is detected, go to EC-283, "Diagnosis Procedure"
PROCEDURE FOR MALFUNCTION B
1. Turn ignition switch ON and wait at least 1 second.
2. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
3. Check 1st trip DTC.
4. If 1st trip DTC is detected, go to EC-283, "Diagnosis Procedure"
.
PROCEDURE FOR MALFUNCTION C
1. Turn ignition switch ON and wait at least 1 second.
2. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
PBIB1164E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0605
0605 Engine control module A) ECM calculation function is malfunctioning.
ECM
B) ECM EEP-ROM system is malfunctioning.
C) ECM self shut-off function is malfunctioning.
Detected items Engine operation condition in fail-safe mode
Malfunction A  ECM stops the electric throttle control actuator control, throttle valve is maintained at a fixed opening (approx.
5 degrees) by the return spring.
 ECM deactivates ASCD operation.
Revision: December 20092009 QX56

P0643 SENSOR POWER SUPPLYEC-285
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P0643 SENSOR POWER SUPPLY
On Board Diagnosis LogicINFOID:0000000003771567
This self-diagnosis has the on
e trip detection logic.
FAIL-SAFE MODE
When the malfunction is detected, ECM ent ers fail-safe mode and the MIL lights up.
DTC Confirmation ProcedureINFOID:0000000003771568
NOTE:
If DTC Confirmation Procedure has been previously conduc ted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 10V at idle.
1. Start engine and let it idle for 1 second.
2. Check DTC.
3. If DTC is detected, go to EC-285, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771569
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body. Refer to EC-85, "Ground Inspection"
.
OK or NG
OK >> GO TO 2.
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: December 20092009 QX56

EC-288
< COMPONENT DIAGNOSIS >[VK56DE]
P0850 PNP SWITCH
P0850 PNP SWITCH
Component DescriptionINFOID:0000000003771570
When the selector lever position is P or N, trans
mission range signal from the TCM is sent to ECM.
On Board Diagnosis LogicINFOID:0000000003771571
DTC Confirmation ProcedureINFOID:0000000003771572
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
WITH CONSULT-III
1. Turn ignition switch ON.
2. Select “P/N POSI SW” in “DATA MONITOR” mode wit h CONSULT-III. Then check the “P/N POSI SW” sig-
nal under the following conditions.
If NG, go to EC-289, "Diagnosis Procedure"
.
If OK, go to following step.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Start engine and warm it up to normal operating temperature.
5. Maintain the following conditions for at least 60 consecutive seconds.
6. Check 1st trip DTC.
7. If 1st trip DTC is detected, go to EC-289, "Diagnosis Procedure"
.
Overall Function CheckINFOID:0000000003771573
Use this procedure to check the overall function of t he transmission range signal circuit. During this check, a
1st trip DTC might not be confirmed.
WITH GST
1. Turn ignition switch ON.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0850
0850 Park/neutral position
switch The transmission range signal is not changed in
the process of engine starting and driving.  Harness or connectors
[The transmission range signal circuit is
open or shorted.]
 Combination meter
TCM
Position (Selector lever) Known-good signal
N or P position ON
Except the above position OFF
ENG SPEED 1,000 - 6,375 rpm
COOLAN TEMP/S More than 70 °C (158 °F)
B/FUEL SCHDL 2.0 - 31.8 msec
VHCL SPEED SE More than 64 km/h (40 MPH)
Selector lever Suitable position
Revision: December 20092009 QX56

P1140, P1145 IVT CONTROL POSITION SENSOR
EC-291
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P1140, P1145 IVT CONTROL POSITION SENSOR
Component DescriptionINFOID:0000000003771575
Intake valve timing control position sensors are located in the front of
cylinder heads in both bank 1 and bank 2.
This sensor uses a Hall IC.
The cam position is determined by the intake camshaft sprocket con-
cave (in four places). The ECM provides feedback to the intake valve
timing control for appropriate target valve open-close timing accord-
ing to drive conditions based on detected cam position.
On Board Diagnosis LogicINFOID:0000000003771576
DTC Confirmation ProcedureINFOID:0000000003771577
1. If DTC Confirmation Procedure has been previously c
onducted, always perform the following before con-
ducting the next step.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Turn ignition switch ON.
c. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-III.
4. Maintain the following conditions for at least 10 seconds.
5. Check 1st trip DTC.
6. If 1st trip DTC is detected, go to EC-291, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771578
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten three ground screws on the body.
SEF359Z
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1140
11 4 0
(Bank 1)
Intake valve timing control
position sensor circuit An excessively high or low voltage from the
sensor is sent to ECM.  Harness or connectors
(Intake valve timing control position
sensor circuit is open or shorted)
 Intake valve timing control position sensor
 Crankshaft position sensor (POS)
 Camshaft positi on sensor (PHASE)
 Accumulation of debris to the signal pick-up portion of the camshaft sprock-
et
P1145
11 4 5
(Bank 2)
ENG SPEED More th
an idle speed
Selector lever P or N position
Revision: December 20092009 QX56

EC-306
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P1421 COLD START CONTROL
P1421 COLD START CONTROL
DescriptionINFOID:0000000003771601
ECM controls ignition timing and engine idle speed when engine is started with prewarming up condition.
This control promotes the activation of three way ca
talyst by heating the catalyst and reduces emissions.
On Board Diagnosis LogicINFOID:0000000003771602
DTC Confirmation ProcedureINFOID:0000000003771603
NOTE:
 If DTC Confirmation Procedure has been previously conducted, always perform the following before con-
ducting the next step.
1. Turn ignition swich OFF and wait at least 10 seconds.
2. Turn ignition swich ON.
3. Turn ignition swich OFF and wait at least 10 seconds.
 If DTC P1421 is displayed with other DTC, firs t perform the trouble diagnosis for other DTC.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11V at idle.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Select “DATA MONITOR” mode with CONSULT-IIl.
4. Check that the “COOLAN TEMP/S” indication is between 4 °C (39 °F) and 36 °C (97 °F).
If “COOLAN TEMP/S” indication is within t he specified value, go to the following step.
If “COOLANT TEMP/S” indication is out of the s pecified value, cool engine down or warm engine up and
go to step 1.
5. Start engine and let it idle for 5 minutes.
6. Check 1st trip DTC.
7. If 1st trip DTC is detected, go to EC-306, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771604
1.PERFORM IDLE AIR VOLUME LEARNING
Perform EC-18, "Idle Air Volume Learning"
.
Is Idle Air Volume Lear ning carried out successfully?
Ye s o r N o
Ye s > > G O T O 2 .
No >> Follow the instruction of Idle Air Volume Learning.
2.CHECK INTAKE SYSTEM
Check for the cause of intake air volume lacking. Refer to the following.
 Crushed intake air passage
 Intake air passage clogging
OK or NG
OK >> GO TO 3.
NG >> Repair or replace malfunctioning part
3.CHECK FUEL INJECTION SYSTEM FUNCTION
Perform EC-169, "DTC Confirmation Procedure"
in DTC P0171, P0174 FUEL INJECTION SYSTEM FUNC-
TION.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1421
1421 Cold start emission reduction
strategy monitoring ECM does not control ignition timing and engine
idle speed properly when engine is started with
prewarming up condition.  Lack of intake air volume
 Fuel injection system
ECM
Revision: December 20092009 QX56

EC-320
< COMPONENT DIAGNOSIS >[VK56DE]
P1554 BATTERY CURRENT SENSOR
P1554 BATTERY CURRENT SENSOR
Component DescriptionINFOID:0000000003771620
The power generation voltage variable control enables fuel con-
sumption to be decreased by reducing the engine load which is
caused by the power generation of the generator. The battery cur-
rent sensor (1) is installed to the battery cable at the negative termi-
nal. The sensor measures the charging/discharging current of the
battery. Based on the sensor signal, ECM judges whether or not the
power generation voltage variable control is performed. When per-
forming the power generation voltage variable control, ECM calcu-
lates the target power generation voltage based on the sensor
signal. And ECM sends the calculated value as the power genera-
tion command value to IPDM E/R. For the details of the power gen-
eration voltage variable control, refer to
CHG-7, "System
Description".
: Vehicle front
CAUTION:
Do not connect the electrical compon ent or the ground wire directly to the battery terminal. The con-
nection causes the malfunction of th e power generation voltage variable control, and then the battery
discharge may occur.
On Board Diagn osis LogicINFOID:0000000003771621
The MIL will not light up for this self-diagnosis.
NOTE:
If DTC P1554 is displayed with DTC P0643, first pe rform the trouble diagnosis for DTC P0643. Refer to
EC-285, "On Board Diagnosis Logic"
.
Overall Function CheckINFOID:0000000003771622
Use this procedure to check the overall function of the bat tery current sensor circuit. During this check, a 1st
trip DTC might not be confirmed.
TESTING CONDITION:
 Before performing the following procedure, confirm th at battery voltage is more than 12.8V at idle.
 Before performing the following procedure, confi rm that all load switches and A/C switch are turned
OFF.
WITH CONSULT-III
1. Start engine and let it idle.
2. Select “BAT CUR SEN” in “DATA MONITOR” mode with CONSULT-III.
3. Check “BAT CUR SEN” indication for 10 seconds.
“BAT CUR SEN” should be above 2,300mV at least once.
4. If NG, go to EC-321, "Diagnosis Procedure"
.
WITH GST
1. Start engine and let it idle.
BBIA0744E
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1554
1554 Battery current sensor performance The output voltage of the battery current
sensor is lower than the specified value
while the battery voltage is high enough.  Harness or connectors
(The sensor circuit is open or shorted.)
 Battery current sensor
Revision: December 20092009 QX56