2001 INFINITI QX4 Electrical

System ChartNBEC0013
Input (Sensor) ECM Function Output (Actuator)
ICamshaft position sensor (PHASE)
ICrankshaft position sensor (REF)
IMass air flow sensor
IEngine coolant temperature sensor
IHeated oxygen sensor 1 (front)
IIgnition switch
IThrottle position sensor
IClosed throttle position switch*3
IPark/neutral position (PNP) switch
IAir conditioner switch
IKnock sensor
IIntake air temperature sensor
IAbsolute pressure sensor
IEVAP control system pressure sensor*1
IBattery voltage
IPower steering oil pressure switch
IVehicle speed sensor
IFuel tank temperature sensor*1
ICrankshaft position sensor (POS)
IHeated oxygen sensor 2 (rear)*2
ITCM (Transmission control module)
IRefrigerant pressure sensor
IElectrical load
IFuel level sensor*1Fuel injection & mixture ratio control Injectors
Electronic ignition system Power transistor
Idle air control system IACV-AAC valve
Fuel pump control Fuel pump relay
On board diagnostic system MIL (On the instrument panel)
Swirl control valve controlSwirl control valve control solenoid
valve
Power valve control VIAS control solenoid valve
Heated oxygen sensor 1 heater (front) con-
trolHeated oxygen sensor 1 heater
(front)
Heated oxygen sensor 2 heater (rear) controlHeated oxygen sensor 2 heater
(rear)
EVAP canister purge flow controlEVAP canister purge volume con-
trol solenoid valve
Air conditioning cut control Air conditioner relay
ON BOARD DIAGNOSIS for EVAP systemIEVAP canister vent control valve
IVacuum cut valve bypass valve
*1: These sensors are not used to control the engine system. They are used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This switch will operate in place of the throttle position sensor to control EVAP parts if the sensor malfunctions.GI
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ENGINE AND EMISSION CONTROL OVERALL SYSTEM
System Chart
EC-27

INSPECTION PROCEDURE=NBEC0028S02
1 INSPECTION START
1. Visually check the following:
IAir cleaner clogging
IHoses and ducts for leaks
IElectrical connectors
IGasket
IThrottle valve and throttle position sensor operation
2. Start engine and warm it up until engine coolant temperature indicator points to the middle of gauge.
Ensure engine stays below 1,000 rpm.
SEF976U
3. Open engine hood and run engine at about 2,000 rpm for about 2 minutes under no-load.
SEF977U
4. Make sure that no DTC is displayed with CONSULT-II or GST.
OK or NG
OK©GO TO 3.
NG©GO TO 2.
2 REPAIR OR REPLACE
Repair or replace components as necessary according to corresponding ªDiagnostic Procedureº.
©GO TO 3.
3 CHECK TARGET IDLE SPEED
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 12.
NG©GO TO 4.
BASIC SERVICE PROCEDURE
Idle Speed/Ignition Timing/Idle Mixture Ratio Adjustment (Cont'd)
EC-46

Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
INT/A TEMP SE
[ÉC] or [ÉF]qqIThe intake air temperature determined
by the signal voltage of the intake air
temperature sensor is indicated.
EVAP SYS PRES [V]qIThe signal voltage of EVAP control sys-
tem pressure sensor is displayed.
ABSOL PRES/SE [V]qIThe signal voltage of the absolute pres-
sure sensor is displayed.
FUEL LEVEL SE [V]qIThe signal voltage of the fuel level sen-
sor is displayed.
START SIGNAL
[ON/OFF]qqIIndicates [ON/OFF] condition from the
starter signal.IAfter starting the engine, [OFF] is dis-
played regardless of the starter signal.
CLSD THL POS
[ON/OFF]qqIIndicates idle position [ON/OFF] com-
puted by ECM according to the throttle
position sensor signal.
CLSD THL/P SW
[ON/OFF]qIIndicates mechanical contact [ON/OFF]
condition of the closed throttle position
switch.
AIR COND SIG
[ON/OFF]qqIIndicates [ON/OFF] condition of the air
conditioner switch as determined by the
air conditioner signal.
P/N POSI SW
[ON/OFF]qqIIndicates [ON/OFF] condition from the
park/neutral position (PNP) switch sig-
nal.
PW/ST SIGNAL
[ON/OFF]qqI[ON/OFF] condition of the power steer-
ing oil pressure switch determined by
the power steering oil pressure signal is
indicated.
LOAD SIGNAL
[ON/OFF]qqIIndicates [ON/OFF] condition from the
electrical load signal and/or lighting
switch.
ON ... rear defogger is operating and/or
lighting switch is on.
OFF ... rear defogger is not operating
and lighting switch is not on.
IGNITION SW
[ON/OFF]qIIndicates [ON/OFF] condition from igni-
tion switch.
SWRL CONT S/V
[ON/OFF]qIThe control condition of the swirl con-
trol valve control solenoid valve (deter-
mined by ECM according to the input
signals) is indicated.
ION ... Swirl control valve is closed.
OFF ... Swirl control valve is opened.
INJ PULSE-B1
[msec]q
IIndicates the actual fuel injection pulse
width compensated by ECM according
to the input signals.IWhen the engine is stopped, a certain
computed value is indicated.
INJ PULSE-B2
[msec]
B/FUEL SCHDL
[msec]qIªBase fuel scheduleº indicates the fuel
injection pulse width programmed into
ECM, prior to any learned on board
correction.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-88

Basic InspectionNBEC0038Precaution:
Perform Basic Inspection without electrical or mechanical
loads applied;
IHeadlamp switch is OFF,
IAir conditioner switch is OFF,
IRear window defogger switch is OFF,
ISteering wheel is in the straight-ahead position, etc.
1 INSPECTION START
1. Check service records for any recent repairs that may indicate a related problem, or a current need for scheduled
maintenance.
2. Open engine hood and check the following:
IHarness connectors for improper connections
IVacuum hoses for splits, kinks and improper connections
IWiring for improper connections, pinches and cuts
IAir cleaner clogging
IHoses and ducts for leaks
SEF983U
©GO TO 2.
2 CHECK THROTTLE OPENER OPERATION-I
Confirm that there is a clearance between throttle drum and stopper.
SEF950Y
OK or NG
OK©GO TO 4.
NG©GO TO 3.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection
EC-101

SYMPTOM
Reference
page
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
Engine
controlCrankshaft position sensor (REF)
circuit
22EC-510
Crankshaft position sensor (POS)
circuitEC-334, 517
Camshaft position sensor
(PHASE) circuit3EC-342
Mass air flow sensor circuit 1
122
222 2EC-150
Heated oxygen sensor 1 (front)
circuit
3EC-192
Engine coolant temperature sen-
sor circuit1 3 3 EC-169, 187
Throttle position sensor circuit 2 2 EC-174
Incorrect throttle position sensor
adjustment3 1 1 1 1 1 1 1 EC-101
Vehicle speed sensor circuit 2 3 3
3EC-417
Knock sensor circuit 2 EC-328
ECM 2233333 3 33EC-444, 117
Start signal circuit 2 EC-621
Park/Neutral position switch circuit 3 3
333 EC-604
Power steering oil pressure switch
circuit2 EC-634
Electrical load signal circuitEC-644
1 - 6: The numbers refer to the order of inspection.
(continued on next page)
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Matrix Chart (Cont'd)
EC-119

TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
42 B/Y Start signal[Ignition switch ªONº]Approximately 0V
[Ignition switch ªSTARTº]9 - 12V
43 R Ignition switch[Ignition switch ªOFFº]0V
[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
44 L PNP switch[Ignition switch ªONº]
IGear position is ªPº or ªNº.Approximately 0V
[Ignition switch ªONº]
IExcept the above gear positionBATTERY VOLTAGE
(11 - 14V)
45 B/RAir conditioner switch
signal[Engine is running]
IBoth A/C switch and blower switch are ªONº.Approximately 0V
[Engine is running]
IA/C switch is ªOFFº.Approximately 5V
47 R/BPower steering oil
pressure switch[Engine is running]
ISteering wheel is being turned.0 - 1.0V
[Engine is running]
ISteering wheel is not being turned.Approximately 5V
48 B ECM ground[Engine is running]
IIdle speedEngine ground
51 BR A/C cut signal[Engine is running]
IAir conditioner is operating.0 - 0.5V
52 PU Electrical load signal[Engine is running]
IRear window defogger: ON
IHi-beam headlamp: ONBATTERY VOLTAGE
(11 - 14V)
[Engine is running]
IElectrical load: OFF0V
55 W/BSwirl control valve con-
trol vacuum check
switch[Engine is running]
IIdle speed
IEngine coolant temperature is between 15 to
50ÉC (59 to 122ÉF).Approximately 5V
[Engine is running]
IIdle speed
IEngine coolant temperature is above 55ÉC
(131ÉF).0 - 1.0V
56 OR/LThrottle position switch
(Closed position)[Engine is running]
IAccelerator pedal fully releasedBATTERY VOLTAGE
(11 - 14V)
[Engine is running]
IAccelerator pedal depressedApproximately 0V
57 B ECM ground[Engine is running]
IIdle speedEngine ground
58 B/P Sensors' ground[Engine is running]
IWarm-up condition
IIdle speedApproximately 0V
59 BFuel level sensor
ground[Engine is running]
IIdle speedApproximately 0V
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
ECM Terminals and Reference Value (Cont'd)
EC-131

DescriptionNBEC0717The specification (SP) value indicates the tolerance of the value that is displayed in ªDATA MONITOR (SPEC)º
mode of CONSULT-II during normal operation of the Engine Control System. When the value in ªDATA MONI-
TOR (SPEC)º mode is within the SP value, the Engine Control System is confirmed OK. When the value in
ªDATA MONITOR (SPEC)º mode is NOT within the SP value, the Engine Control System may have one or
more malfunctions.
The SP value is used to detect malfunctions that may affect the Engine Control System, but will not light the
MIL.
The SP value will be displayed for the following three items:
IB/FUEL SCHDL (The fuel injection pulse width programmed into ECM prior to any learned on board cor-
rection)
IA/F ALPHA-B1/B2 (The mean value of air-fuel ratio feedback correction factor per cycle)
IMAS A/F SE-B1 (The signal voltage of the mass air flow sensor)
Testing ConditionNBEC0718IVehicle driven distance: More than 5,000 km (3,100 miles)
IBarometric pressure: 101.3 kPa (760.0 mmHg, 29.92 inHg)±3 kPa (22.5 mmHg, 0.89 inHg)
IAtmospheric temperature: 20 - 30ÉC (68 - 86ÉF)
IEngine coolant temperature: 75 - 95ÉC (167 - 203ÉF)
ITransmission: Warmed-up*1
IElectrical load: Not applied*2
IEngine speed: Idle
*1: For A/T models, after the engine is warmed up to normal operating temperature, drive vehicle until ªFLUID
TEMP SEº (A/T fluid temperature sensor signal) indicates less than 0.9V.
*2: Rear window defogger switch, air conditioner switch, lighting switch are ªOFFº. Cooling fans are not oper-
ating. Steering wheel is straight ahead.
SEF601Z
Inspection ProcedureNBEC0719NOTE:
Perform ªDATA MONITOR (SPEC)º mode in maximum scale dis-
play.
1. Perform ªBasic Inspectionº, EC-101.
2. Confirm that the testing conditions indicated above are met.
3. Select ªB/FUEL SCHDLº, ªA/F ALPHA-B1º, ªA/F ALPHA-B2º
and ªMAS A/F SE-B1º in ªDATA MONITOR (SPEC)º mode with
CONSULT-II.
4. Make sure that monitor items are within the SP value.
5. If NG, go to ªDiagnostic Procedureº, EC-137.
TROUBLE DIAGNOSIS Ð SPECIFICATION VALUE
Description
EC-136

DescriptionNBEC0045Intermittent incidents (I/I) may occur. In many cases, the problem resolves itself (the part or circuit function
returns to normal without intervention). It is important to realize that the symptoms described in the custom-
er's complaint often do not recur on (1st trip) DTC visits. Realize also that the most frequent cause of I/I
occurrences is poor electrical connections. Because of this, the conditions under which the incident occurred
may not be clear. Therefore, circuit checks made as part of the standard diagnostic procedure may not indi-
cate the specific problem area.
COMMON I/I REPORT SITUATIONSNBEC0045S01
STEP in Work Flow Situation
II The CONSULT-II is used. The SELF-DIAG RESULTS screen shows time data other than ª0º or ª[1t]º.
III The symptom described by the customer does not recur.
IV (1st trip) DTC does not appear during the DTC Confirmation Procedure.
VI The Diagnostic Procedure for PXXXX does not indicate the problem area.
Diagnostic ProcedureNBEC0046
1 INSPECTION START
Erase (1st trip) DTCs. Refer to ªHOW TO ERASE EMISSION Ð RELATED INFORMATIONº, EC-72.
©GO TO 2.
2 CHECK GROUND TERMINALS
Check ground terminals for corroding or loose connection.
Refer to GI-30, ªGROUND INSPECTIONº.
OK or NG
OK©GO TO 3.
NG©Repair or replace.
3 SEARCH FOR ELECTRICAL INCIDENT
Perform GI-36, ªIncident Simulation Testsº.
OK or NG
OK©GO TO 4.
NG©Repair or replace.
4 CHECK CONNECTOR TERMINALS
Refer to GI-27, ªHow to Check Enlarged Contact Spring of Terminalº.
OK or NG
OK©INSPECTION END
NG©Repair or replace connector.
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT
Description
EC-140