INFINITI QX56 2011 Factory Service Manual

P1574 ASCD VEHICLE SPEED SENSOREC-447
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P1574 ASCD VEHICLE SPEED SENSOR
DescriptionINFOID:0000000006288349
The ECM receives two vehicle speed signals by the CAN
communication line. One is sent from “combination
meter”, and the other is from TCM (Transmission cont rol module). The ECM uses these signals for ASCD con-
trol. Refer to EC-48, "
AUTOMATIC SPEED CONTROL DEVICE (ASCD) : System Description" for ASCD func-
tions.
DTC LogicINFOID:0000000006288350
DTC DETECTION LOGIC
NOTE:
 If DTC P1574 is displayed with DTC UXXXX, perform the trouble diagnosis for DTC UXXXX.
 If DTC P1574 is displayed with DTC P0500, perform the trouble diagnosis for DTC P0500. Refer to
EC-356, "
DTC Logic".
 If DTC P1574 is displayed with DTC P0605, perform the trouble diagnosis for DTC P0605. Refer to
EC-376, "
DTC Logic".
 If DTC P1574 is displayed with DTC P0607, perform the trouble diagnosis for DTC P0607. Refer to
EC-378, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
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.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine (VDC switch OFF).
2. Drive the vehicle at more than 40 km/h (25 MPH). CAUTION:
Always drive vehicle at a safe speed.
NOTE:
This procedure may be conducted with the drive wheel s 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.
3. Check DTC.
Is DTC detected?
YES >> Proceed to EC-449, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288351
1.CHECK DTC WITH TCM
Check DTC with TCM. Refer to TM-61, "
CONSULT-III Function (TRANSMISSION)".
Is the inspection result normal?
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1574 ASCD VHL SPD SEN
(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 elec tric unit (control
unit)
 Wheel sensor
TCM
ECM
Revision: 2010 May2011 QX56

EC-448
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1574 ASCD VEHICL
E SPEED SENSOR
YES >> GO TO 2.
NO >> Perform Diagnosis Procedure corresponding to the DTC indicated.
2.CHECK DTC WITH “ABS ACTUATOR A ND ELECTRIC UNIT (CONTROL UNIT)”
Refer to BRC-40, "
CONSULT-III Function".
Is the inspection result normal?
YES >> GO TO 3.
NO >> Perform Diagnosis Procedure corresponding to the DTC indicated.
3.CHECK DTC WITH “COMBINATION METER”
Refer to MWI-30, "
CONSULT-III Function".
>> INSPECTION END
Revision: 2010 May2011 QX56

P1574 ICC VEHICLE SPEED SENSOR
EC-449
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P1574 ICC VEHICLE SPEED SENSOR
DescriptionINFOID:0000000006288352
The ECM receives two vehicle speed signals by the CAN
communication line. One is sent from “combination
meter”, and the other is from TCM (Transmission cont rol module). The ECM uses these signals for ICC con-
trol. Refer to CCS-12, "
System Description" for ICC functions.
DTC LogicINFOID:0000000006288353
DTC DETECTION LOGIC
NOTE:
If DTC P1574 is displayed with DTC UXXXX, first perform the tr ouble diagnosis for DTC UXXXX.
 If DTC P1574 is displayed with DT C P0500, first perform the trouble diagnosis for DTC P0500. Refer
to EC-356, "
DTC Logic".
 If DTC P1574 is displayed with DT C P0605, first perform the trouble diagnosis for DTC P0605. Refer
to EC-376, "
DTC Logic".
 If DTC P1574 is displayed with DT C P0607, first perform the trouble diagnosis for DTC P0607. Refer
to EC-378, "
DTC Logic".
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
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.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine (VDC switch OFF).
2. Drive the vehicle at more than 40 km/h (25 MPH). CAUTION:
Always drive vehicle at a safe speed.
NOTE:
This procedure may be conducted with the drive wheel s 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.
3. Check DTC.
Is DTC detected?
YES >> Proceed to EC-449, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006288354
1.CHECK DTC WITH TCM
Check DTC with TCM. Refer to TM-61, "
CONSULT-III Function (TRANSMISSION)".
Is the inspection result normal?
YES >> GO TO 2.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1574 ASCD VHL SPD SEN
(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: 2010 May2011 QX56

EC-450
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1574 ICC VEHICLE SPEED SENSOR
NO >> Perform Diagnosis Procedure corresponding to the DTC indicated.
2.CHECK DTC WITH “ABS ACTUATOR A
ND ELECTRIC UNIT (CONTROL UNIT)”
Refer to BRC-40, "
CONSULT-III Function".
Is the inspection result normal?
YES >> GO TO 3.
NO >> Perform Diagnosis Procedure corresponding to the DTC indicated.
3.CHECK DTC WITH “COMBINATION METER”
Check combination meter function.
Refer to MWI-30, "
CONSULT-III Function".
>> INSPECTION END
Revision: 2010 May2011 QX56

P1606 VVEL CONTROL MODULEEC-451
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P1606 VVEL CONTROL MODULE
DTC LogicINFOID:0000000006217951
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
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:
Before performing the following procedure, confi rm that battery voltage is 10 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON and wait at least 1 second.
2. Check DTC.
Is DTC detected?
YES >> Go to EC-451, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217952
1.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Erase DTC.
3. Perform DTC Confirmation Procedure. See EC-451, "
DTC Logic".
Is the DTC P1606 displayed again?
YES >> Replace VVEL control module. Refer to EC-536, "Removal and Installation".
NO >> INSPECTION END
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1606 VVEL CONTROL MODULE
(VVEL contro
l module)  VVEL control module ca
lculation function is
malfunctioning.
 VVEL EEP-ROM system is malfunctioning. VVEL control module
Revision: 2010 May2011 QX56

EC-452
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1607 VVEL CONTROL MODULE
P1607 VVEL CONTROL MODULE
DTC LogicINFOID:0000000006217953
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
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:
Before performing the following procedure, confi rm that battery voltage is 10 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Start engine and let it idle for at least 1 second.
2. Check DTC.
Is DTC detected?
YES >> Go to EC-452, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217954
1.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Erase DTC.
3. Perform DTC Confirmation Procedure. See EC-452, "
DTC Logic".
Is the DTC P1607 displayed again?
YES >> Replace VVEL control module. Refer to EC-536, "Removal and Installation".
NO >> INSPECTION END
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1607 VVEL CONTROL MODULE
(VVEL control module circuit)  The internal circui
t of the VVEL control
module is malfunctioning.  VVEL control module
Revision: 2010 May2011 QX56

P1608 VVEL SENSOR POWER SUPPLY
EC-453
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P1608 VVEL SENSOR POWER SUPPLY
DTC LogicINFOID:0000000006217955
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
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:
Before performing the following procedure, confi rm that battery voltage is 10 V or more at idle.
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON and wait at least 1 second.
2. Check DTC.
Is DTC detected?
YES >> Go to EC-453, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217956
1.CHECK VVEL CONTROL SHAFT POSITI ON SENSOR POWER SUPPLY CIRCUIT-I
1. Disconnect VVEL control shaft pos ition sensor harness connector.
2. Turn ignition switch ON.
3. Check the voltage between VVEL control shaf t position sensor harness connector and ground.
Is the inspection result normal?
YES >> GO TO 5.
NO >> GO TO 2.
2.CHECK VVEL CONTROL SHAFT POSITI ON SENSOR POWER SUPPLY CIRCUIT-II
1. Turn ignition switch OFF.
2. Disconnect VVEL control module harness connector.
3. Check the continuity between VVEL control shaft position sensor harness connector and VVEL control
module harness connector.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1608 VVEL SENSOR POWER/CIRC
(VVEL sensor power supply circuit) VVEL control module detects a voltage
of power source for sensor is excessive-
ly low or high.  Harness or connectors
(VVEL control shaft position sensor
power supply circuit is open or shorted.)
 VVEL control shaf t position sensor
 VVEL control module
VVEL control shaft position sensor Ground Voltage
Bank Connector Terminal
1F72 3
Ground Approx. 5V
6
2F70 3
6
Revision: 2010 May2011 QX56

EC-454
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1608 VVEL SENSOR POWER SUPPLY
4. Also check harness for short to ground and power.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between VVEL control shaft position sensor and VVEL control module
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connectors.
4.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
Is the inspection result normal?
YES >> Replace VVEL control module. Refer to EC-536, "Removal and Installation".
NO >> Repair or replace.
5.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
Is the inspection result normal?
YES >> GO TO 6.
NO >> Repair or replace.
6.REPLACE VVEL LADDER ASSEMBLY
Replace VVEL ladder assembly. Refer to EM-75, "
Removal and Installation".
>> NSPECTION END
VVEL control shaft position sensor VVEL control module Continuity
Bank Connector Terminal Connector Terminal
1F72 3
F56 7
Existed
620
2F70 39
622
Revision: 2010 May2011 QX56

P1805 BRAKE SWITCHEC-455
< DTC/CIRCUIT DIAGNOSIS > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
P1805 BRAKE SWITCH
DTC LogicINFOID:0000000006217957
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
1.PERFORM DTC CONFIRMATION PROCEDURE
1. Turn ignition switch ON.
2. Fully depress the brake pedal for at least 5 seconds.
3. Erase the DTC.
4. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >> Go to EC-455, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis ProcedureINFOID:0000000006217958
1.CHECK STOP LAMP SWITCH CIRCUIT
1. Turn ignition switch OFF.
2. Check for stop lamp illumination under the following conditions.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 2.
2.CHECK STOP LAMP SWIT CH POWER SUPPLY CIRCUIT
1. Disconnect stop lamp switch harness connector.
2. Check the voltage between stop lamp switch harness connector and ground.
Is the inspection result normal?
YES >> GO TO 4.
NO >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
 10 A fuse (No. 7)
 Harness for open or short between stop lamp switch and battery
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connectors.
DTC No. Trouble diagnosis name
(Trouble diagnosis content) DTC detecting condition Possible cause
P1805 BRAKE SW/CIRCUIT
(Brake switch) A brake switch signal is not sent to ECM
for extremely long time while the vehicle
is being driven.  Harness or connectors
(Stop lamp switch circuit is open or shorted.)
 Stop lamp switch
Condition Stop lamp
Brake pedal Fully released Not illuminated
Slightly depressed Illuminated
Stop lamp switch Ground Voltage
Connector Terminal
E115 1 Ground Battery voltage
Revision: 2010 May2011 QX56

EC-456
< DTC/CIRCUIT DIAGNOSIS >[VK56VD]
P1805 BRAKE SWITCH
4.CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect stop lamp switch harness connector.
2. Disconnect ECM harness connector.
3. Check the continuity between stop lamp s witch harness connector and ECM harness connector.
4. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES >> GO TO 6.
NO >> GO TO 5.
5.DETECT MALFUNCTIONING PART
Check the following.
 Harness for open or short between ECM and stop lamp switch
 Loose or poor connection for each connector and harness
>> Repair open circuit, short to ground or short to power in harness or connectors.
6.CHECK STOP LAMP SWITCH
Refer to EC-456, "
Component Inspection (Stop Lamp Switch)".
Is the inspection result normal?
YES >> GO TO 7.
NO >> Replace stop lamp switch. Refer to BR-20, "
Removal and Installation".
7.CHECK INTERMITTENT INCIDENT
Refer to GI-40, "
Intermittent Incident".
>> INSPECTION END
Component Inspection (Stop Lamp Switch)INFOID:0000000006217959
1.CHECK STOP LAMP SWITCH-I
1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.
3. Check the continuity between stop lamp switch terminals under the following conditions.
Is the inspection result normal?
YES >> INSPECTION END
NO >> GO TO 2.
2.CHECK STOP LAMP SWITCH-II
1. Adjust stop lamp switch installation. Refer to BR-21, "
Inspection and Adjustment".
2. Check the continuity between stop lamp switch terminals under the following conditions.
Is the inspection result normal?
Stop lamp switch ECM Continuity
Connector Terminal Connector Terminal
E115 2 E80 158 Existed
Terminals Condition Continuity
1 and 2 Brake pedal Fully released Not existed
Slightly depressed Existed
Terminals Condition Continuity
1 and 2 Brake pedal Fully released Not existed
Slightly depressed Existed
Revision: 2010 May2011 QX56