2009 INFINITI QX56 sensor

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

P1554 BATTERY CURRENT SENSOREC-321
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2. Check voltage between ECM terminal 71 (battery current sensor
signal) and ground for 10 seconds.
The voltage should be ab ove 2.3V at least once.
3. If NG, go to EC-321, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771623
1.CHECK GROUND CONNECTIONS
1. Turn ignition switch OFF.
2. Loosen and retighten ground screws on the body. Refer to EC-85, "Ground Inspection"
.
OK or NG
OK >> GO TO 2.
NG >> Repair or replace ground connections.
2.CHECK BATTERY CURRENT SENSOR POWER SUPPLY CIRCUIT
1. Disconnect battery current sensor (1) harness connector.
2. Turn ignition switch ON. : Vehicle front
3. Check voltage between battery current sensor terminal 1 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
PBIB2616E
BBIA0354E
BBIA0744E
Voltage: Approximately 5V
PBIA9891J
Revision: December 20092009 QX56

EC-322
< COMPONENT DIAGNOSIS >[VK56DE]
P1554 BATTERY CURRENT SENSOR
Check the following.
 Harness connectors E5, F14
 Harness for open or short between battery current sensor and ECM
>> Repair open circuit or short to ground or short to power in harness or connectors.
4.CHECK BATTERY CURRENT SENSOR GRO UND CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between battery curr ent sensor terminal 2 and ECM terminal 67.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors E5, F14
 Harness for open or short between battery current sensor and ECM
>> Repair open circuit or short to ground or short to power in harness or connectors.
6.CHECK BATTERY CURRENT SENSOR INPUT SI GNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between battery curr ent sensor terminal 3 and ECM terminal 71.
Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 8.
NG >> GO TO 7.
7.DETECT MALFUNCTIONING PART
Check the following.
 Harness connectors E2, F32
 Harness for open or short between battery current sensor and ECM
>> Repair open circuit or short to ground or short to power in harness or connectors.
8.CHECK BATTERY CURRENT SENSOR
Refer to EC-322, "Component Inspection"
.
OK or NG
OK >> GO TO 9.
NG >> Replace battery negative cable assembly.
9.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "How to Check Terminal"
and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000003771624
BATTERY CURRENT SENSOR
Continuity should exist.
Continuity should exist.
Revision: December 20092009 QX56

P1554 BATTERY CURRENT SENSOREC-323
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1. Reconnect harness connectors disconnected.
2. Disconnect battery negative cable (1).
3. Install jumper cable (A) between battery negative terminal and
body ground.
4. Turn ignition switch ON.
5. Check voltage between ECM terminal 71 (battery current sensor signal) and ground.
6. If NG, replace battery negative cable assembly.
BBIA0745E
Voltage: Approximately 2.5V
PBIB2617E
Revision: December 20092009 QX56

EC-344
< COMPONENT DIAGNOSIS >[VK56DE]
P1574 ICC VEHICLE SPEED SENSOR
P1574 ICC VEHICLE SPEED SENSOR
Component DescriptionINFOID:0000000003771648
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:0000000003771649
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-86, "On Board Diagnosis Logic"
.
 If DTC P1574 is displayed with DTC P0607, first pe rform the trouble diagnosis for DTC P0607. Refer
to EC-284, "On Board Diagnosis Logic"
.
 If DTC P1574 is displayed with DTC P0500, first pe rform the trouble diagnosis for DTC P0500. Refer
to EC-271, "On Board Diagnosis Logic"
.
 If DTC P1574 is displayed with DTC P0605, first pe rform the trouble diagnosis for DTC P0605. Refer
to EC-282, "On Board Diagnosis Logic"
.
DTC Confirmation ProcedureINFOID:0000000003771650
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.
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.
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-344, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771651
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.
2.CHECK DTC WITH “ABS ACTUATOR A ND ELECTRIC UNIT (CONTROL UNIT)”
Refer to BRC-24, "CONSULT-III Function (ABS)"
.
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: December 20092009 QX56

P1574 ICC VEHICLE SPEED SENSOR
EC-345
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OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3.CHECK COMBINATION METER FUNCTION
Refer to MWI-5
.
>> INSPECTION END
Revision: December 20092009 QX56

EC-346
< COMPONENT DIAGNOSIS >[VK56DE]
P1574 ASCD VEHICL
E SPEED SENSOR
P1574 ASCD VEHICLE SPEED SENSOR
Component DescriptionINFOID:0000000003771652
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:0000000003771653
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-86, "DTC Confirmation Procedure"
.
 If DTC P1574 is displayed with DTC P0607, first pe rform the trouble diagnosis for DTC P0607. Refer
to EC-284, "On Board Diagnosis Logic"
.
 If DTC P1574 is displayed with DTC P0500, first pe rform the trouble diagnosis for DTC P0500. Refer
to EC-271, "On Board Diagnosis Logic"
.
 If DTC P1574 is displayed with DTC P0605, first pe rform the trouble diagnosis for DTC P0605. Refer
to EC-282, "On Board Diagnosis Logic"
.
DTC Confirmation ProcedureINFOID:0000000003771654
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.
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.
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-346, "Diagnosis Procedure"
.
Diagnosis ProcedureINFOID:0000000003771655
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.
2.CHECK DTC WITH ABS ACTUATOR AN D ELECTRIC UNIT (CONTROL UNIT)
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: December 20092009 QX56

P1574 ASCD VEHICLE SPEED SENSOREC-347
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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: December 20092009 QX56