INFINITI QX4 2001 Factory Service Manual

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

Diagnostic ProcedureNBEC0720
SEF613ZB
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TROUBLE DIAGNOSIS Ð SPECIFICATION VALUE
Diagnostic Procedure
EC-137

SEF768Z
TROUBLE DIAGNOSIS Ð SPECIFICATION VALUE
Diagnostic Procedure (Cont'd)
EC-138

SEF615Z
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TROUBLE DIAGNOSIS Ð SPECIFICATION VALUE
Diagnostic Procedure (Cont'd)
EC-139

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

ECM Terminals and Reference ValueNBEC0648Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
26 L/BECM relay
(Self shutt-off)[Engine is running]
[Ignition switch ªOFFº]
IFor a few seconds after turning ignition switch
ªOFFº0 - 1.5V
[Ignition switch ªOFFº]
IA few seconds passed after turning ignition
switch ªOFFºBATTERY VOLTAGE
(11 - 14V)
43 R Ignition switch[Ignition switch ªOFFº]0V
[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
48 B ECM ground[Engine is running]
IIdle speedEngine ground
[Probe this terminal with (±)
tester probe when measuring]
57 B ECM ground[Engine is running]
IIdle speedEngine ground
12
67W/RPower supply for ECM
(Buck-up)[Ignition switch ªOFFº]BATTERY VOLTAGE
(11 - 14V)
108 B ECM ground[Engine is running]
IIdle speedEngine ground
11 0
11 2B/W
B/WPower supply for ECM[Ignition switch ªONº]BATTERY VOLTAGE
(11 - 14V)
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TROUBLE DIAGNOSIS FOR POWER SUPPLY
ECM Terminals and Reference Value
EC-141

Main Power Supply and Ground Circuit
WIRING DIAGRAMNBEC0047
MEC940C
TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit
EC-142

MEC941C
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TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit (Cont'd)
EC-143

DIAGNOSTIC PROCEDURENBEC0049
1 INSPECTION START
Start engine.
Is engine running?
YesorNo
Ye s©GO TO 9.
No©GO TO 2.
2 CHECK ECM POWER SUPPLY CIRCUIT-I
1. Turn ignition switch ªOFFº and then ªONº.
2. Check voltage between ECM terminal 43 and ground with CONSULT-II or tester.
SEF291X
OK or NG
OK©GO TO 4.
NG©GO TO 3.
3 DETECT MALFUNCTIONING PART
Check the following.
I10A fuses
IHarness connectors M33, F22
IHarness for open or short between ECM and ignition switch
©Repair harness or connectors.
4 CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-I
1. Turn ignition switch ªOFFº.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals 48, 57, 106, 108 and engine ground.
Refer to WIRING DIAGRAM.
Continuity should exist.
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.
TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit (Cont'd)
EC-144

5 CHECK POWER SUPPLY-II
1. Disconnect ECM relay.
SEF681UB
2. Check voltage between ECM relay terminals 1, 5 and ground with CONSULT-II or tester.
SEF956Y
OK or NG
OK©GO TO 7.
NG©GO TO 6.
6 DETECT MALFUNCTIONING PART
Check the following.
I7.5A and 10A fuses
IHarness for open or short between ECM relay and battery
©Repair open circuit or short to ground or short to power in harness or connectors.
7 CHECK OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 26 and ECM relay terminal 2.
Continuity should exist.
2. Also check harness for short to ground and short to power.
OK or NG
OK©Go to ªDTC P1320 IGNITION SIGNALº, EC-499.
NG©GO TO 8.
8 DETECT MALFUNCTIONING PART
Check the following.
IHarness connectors E1, M1 and M32, F23
IHarness for open or short between ECM relay and ECM
©Repair open circuit or short to ground or short to power in harness or connectors.
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TROUBLE DIAGNOSIS FOR POWER SUPPLY
Main Power Supply and Ground Circuit (Cont'd)
EC-145