INFINITI QX56 2008 Factory Service Manual

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

P1574 ICC VEHICLE SPEED SENSOR
EC-353
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2.CHECK DTC WITH “ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)”
Refer to BRC-24, "
CONSULT-III Function (ABS)".
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3.CHECK COMBINATION METER FUNCTION
Refer to MWI-5
.
>> INSPECTION END
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

P1574 ASCD VEHICLE SPEED SENSOREC-355
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2.CHECK DTC WITH ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
Refer to BRC-24, "
CONSULT-III Function (ABS)".
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3.CHECK COMBINATION METER FUNCTION
Check combination meter function.
Refer to MWI-5
.
>> INSPECTION END
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

P1805 BRAKE SWITCHEC-357
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1. Disconnect stop lamp switch harness connector.
2. Check voltage between stop lamp switch terminal 3 and ground
with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors M31, E152
• Fuse block (J/B) connector M60
• 10A fuse
• Harness for open and short between stop lamp switch and battery
>> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK STOP LAMP SWITCH INPUT SI GNAL CIRCUIT FOR OPEN AND SHORT
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.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK STOP LAMP SWITCH
Refer to EC-358, "
Component Inspection".
OK or NG
OK >> GO TO 6.
NG >> Replace stop lamp switch.
6.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
BBIA0373E
Voltage: Battery voltage
PBIB2102E
Continuity should exist.
Revision: March 2010 2008 QX56

EC-358
< COMPONENT DIAGNOSIS >[VK56DE]
P1805 BRAKE SWITCH
Component Inspection
INFOID:0000000001528801
STOP LAMP SWITCH
1. Disconnect stop lamp switch harness connector.
2. Check continuity between stop lamp switch terminals 3 and 4 under the following conditions.
3. If NG, adjust stop lamp switch installation, refer to BR-15,
"Inspection and Adjustment", and perform step 2 again.
BBIA0373E
ConditionsContinuity
Brake pedal: Fully released Should not exist.
Brake pedal: Slightly depressed Should exist.
PBIB2103E
Revision: March 2010 2008 QX56

P2100, P2103 THROTTLE CONTROL MOTOR RELAYEC-359
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P2100, P2103 THROTTLE CONTROL MOTOR RELAY
Component DescriptionINFOID:0000000001528860
Power supply for the throttle control motor is provided to the ECM via throttle control motor relay. The throttle
control motor relay is ON/OFF controlled by the ECM. When the ignition switch is turned ON, the ECM sends
an ON signal to throttle control motor relay and batte
ry voltage is provided to the ECM. When the ignition
switch is turned OFF, the ECM sends an OFF signal to throttle control motor relay and battery voltage is not
provided to the ECM.
On Board Diagnosis LogicINFOID:0000000001528862
These self-diagnoses have the on e trip detection logic.
FA I L - S A F E M O D E
When the malfunction is detected, ECM enters fail-safe mode and the MlL lights up.
DTC Confirmation ProcedureINFOID:0000000001528863
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 DTC P2100
With CONSULT-III
1. Turn ignition switch ON and wait at least 2 seconds.
2. Start engine and let it idle for 5 seconds.
3. Check DTC.
4. If DTC is detected, go to EC-360, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
PROCEDURE FOR DTC P2103
TESTING CONDITION:
Before performing the following procedure, c onfirm that battery voltage is more than 8V.
With CONSULT-III
1. Turn ignition switch ON and wait at least 1 second.
2. Check DTC.
3. If DTC is detected, go to EC-360, "
Diagnosis Procedure".
With GST
Follow the procedure “With CONSULT-III” above.
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P2100
2100 Throttle control motor
relay circuit open ECM detects a voltage of power source for
throttle control motor is excessively low. • Harness or connectors
(Throttle control motor relay circuit is
open)
• Throttle control motor relay
P2103
2103 Throttle control motor
relay circuit short ECM detect the throttle control motor relay is
stuck ON. • Harness or connectors
(Throttle control motor relay circuit is
shorted)
• Throttle control motor relay
Engine operating 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.
Revision: March 2010 2008 QX56

EC-360
< COMPONENT DIAGNOSIS >[VK56DE]
P2100, P2103 THROTTLE
CONTROL MOTOR RELAY
Diagnosis Procedure
INFOID:0000000001528865
1.CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY CIRCUIT-I
1. Turn ignition switch OFF.
2. Check voltage between ECM terminal 104 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2.CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY CIRCUIT-II
1. Disconnect ECM harness connector.
2. Disconnect IPDM E/R harness connector E122.
3. Check continuity between ECM terminal 104 and IPDM E/R terminal 47. Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
3.CHECK FUSE
1. Disconnect 20A fuse.
2. Check 20A fuse for blown.
OK or NG
OK >> GO TO 7.
NG >> Replace 20A fuse.
4.CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-I
Check voltage between ECM terminal 3 and ground under the fol-
lowing conditions with CONSULT-III or tester.
OK or NG
OK >> GO TO 7.
NG >> GO TO 5.
5.CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-II
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Disconnect IPDM E/R harness connector E119.
4. Check continuity between ECM terminal 3 and IPDM E/R terminal 6. Refer to Wiring Diagram.
5. Also check harness for short to ground and short to power. Voltage: Battery voltage
PBIB1171E
Continuity should exist.
Ignition switch
Voltage
OFF Approximately 0V
ON Battery voltage
(11 - 14V)
MBIB0028E
Continuity should exist.
Revision: March 2010 2008 QX56

P2100, P2103 THROTTLE CONTROL MOTOR RELAYEC-361
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OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
6.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors E2, F32
• Harness for open or short between ECM and IPDM E/R
>> Repair open circuit or short to ground or short to power in harness or connectors.
7.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
OK or NG
OK >> Replace IPDM E/R. Refer to PCS-34, "Removal and Installation of IPDM E/R" .
NG >> Repair or replace harness or connectors.
Revision: March 2010 2008 QX56