2001 INFINITI QX4 IDX

SEF139P
Generic Scan Tool (GST)=NBEC0035DESCRIPTIONNBEC0035S01Generic Scan Tool (OBDII scan tool) complying with SAE J1978
has 8 different functions explained on the next page.
ISO9141 is used as the protocol.
The name ªGSTº or ªGeneric Scan Toolº is used in this service
manual.
SEF941Y
GST INSPECTION PROCEDURENBEC0035S021. Turn ignition switch OFF.
2. Connect GST to data link connector, which is located under LH
dash panel near the fuse box cover.
SEF398S
3. Turn ignition switch ON.
4. Enter the program according to instruction on the screen or in
the operation manual.
(*: Regarding GST screens in this section, sample screens are
shown.)
SEF416S
5. Perform each diagnostic mode according to each service pro-
cedure.
For further information, see the GST Operation Manual of the
tool maker.
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Generic Scan Tool (GST)
EC-95

MEF036D
IntroductionNBEC0036
SEF233G
SEF234G
The engine has an ECM to control major systems such as fuel
control, ignition control, idle air control system, etc. The ECM
accepts input signals from sensors and instantly drives actuators.
It is essential that both input and output signals are proper and
stable. At the same time, it is important that there are no problems
such as vacuum leaks, fouled spark plugs, or other problems with
the engine.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electric connections or improper wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the problems. A road
test with CONSULT-II (or GST) or a circuit tester connected should
be performed. Follow the ªWork Flowº on EC-99.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such problems, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A ªDiagnostic Worksheetº like the
example on next page should be used.
Start your diagnosis by looking for ªconventionalº problems first.
This will help troubleshoot driveability problems on an electronically
controlled engine vehicle.
SEF907L
DIAGNOSTIC WORKSHEETNBEC0036S01There are many operating conditions that lead to the malfunction
of engine components. A good grasp of such conditions can make
trouble-shooting faster and more accurate.
In general, each customer feels differently about a problem. It is
important to fully understand the symptoms or conditions for a
customer complaint.
Utilize a diagnostic worksheet like the one on the next page in order
to organize all the information for troubleshooting.
Some conditions may cause the MIL to come on steady or blink and
DTC to be detected. Examples:
IVehicle ran out of fuel, which caused the engine to misfire.
IFuel filler cap was left off or incorrectly screwed on, allowing
fuel to evaporate into the atmosphere.
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TROUBLE DIAGNOSIS Ð INTRODUCTION
Introduction
EC-97

Work FlowNBEC0037
SEF510ZF
*1 EC-117
*2 If time data of ªSELF-DIAG
RESULTSº is other than ª0º or
ª[1t]º, perform ªTROUBLE DIAG-
NOSIS FOR INTERMITTENT
INCIDENTº, EC-140.
*3 If the incident cannot be verified,
perform ªTROUBLE DIAGNOSIS
FOR INTERMITTENT INCIDENTº,
EC-140.*4 If the on board diagnostic system
cannot be performed, check main
power supply and ground circuit.
Refer to ªTROUBLE DIAGNOSIS
FOR POWER SUPPLYº, EC-142.
*5 If malfunctioning part cannot bedetected, perform ªTROUBLE
DIAGNOSIS FOR INTERMIT-
TENT INCIDENTº, EC-140.
*6 EC-66
*7 EC-136
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TROUBLE DIAGNOSIS Ð INTRODUCTION
Work Flow
EC-99

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

6 CHECK VACUUM HOSE
1. Stop engine.
2. Remove the vacuum hose.
3. Check the vacuum hose for splits, kinks and clogging.
SEF109L
OK or NG
OK©1. Clean vacuum port by blowing air.
2. GO TO 4.
NG©1. Replace vacuum hose.
2. GO TO 4.
7 CHECK THROTTLE DRUM OPERATION
Confirm that throttle drum moves to contact the stopper.
SEF950Y
OK or NG
OK©GO TO 10.
NG©GO TO 8.
8 CHECK ACCELERATOR WIRE INSTALLATION
1. Stop engine.
2. Check accelerator wire for slack.
OK or NG
OK©GO TO 9.
NG©1. Adjust accelerator wire. Refer to FE-3, ªAdjusting Accelerator Wireº.
2. GO TO 7.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-103

11 CHECK THROTTLE POSITION SWITCH CLOSED POSITION-II
With CONSULT-II
1. Turn ignition switch ªONº.
2. Select ªTP SW/TP SEN IDLE POSI ADJº in ªWORK SUPPORTº mode with CONSULT-II.
3. Read ªCLSD THL/P SWº signal under the following conditions.
IInsert a 0.05 mm (0.0020 in) and 0.15 mm (0.0059 in) feeler gauge alternately between stopper and throttle drum as
shown in the figure and check the signal.
SEF953Y
SEF987Y
ªCLSD THL/P SWº signal should remain ªONº while inserting 0.05 mm (0.0020 in) feeler gauge.
ªCLSD THL/P SWº signal should remain ªOFFº while inserting 0.15 mm (0.0059 in) feeler gauge.
OK or NG
OK©GO TO 14.
NG©GO TO 12.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-105

13 ADJUSTMENT THROTTLE POSITION SWITCH CLOSED POSITION-II
With CONSULT-II
1. Temporarily tighten sensor body fixing bolts as follows.
IGradually move the sensor body clockwise and stop it when ªCLSD THL/P SWº signal switches from ªOFFº to
ªONº, then temporarily tighten sensor body fixing bolts.
SEF954Y
2. Make sure two or three times that the signal is ªONº when the throttle valve is closed and ªOFFº when it is opened.
3. Remove 0.05 mm (0.0020 in) feeler gauge then insert 0.15 mm (0.0059 in) feeler gauge.
4. Make sure two or three times that the signal remains ªOFFº when the throttle valve is closed.
5. Tighten throttle position sensor.
6. Check the ªCLSD THL/P SWº signal again.
The signal remains ªOFFº while closing throttle valve.
OK or NG
OK©GO TO 14.
NG©GO TO 12.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-107

15 CHECK THROTTLE POSITION SWITCH CLOSED POSITION-II
1. Disconnect closed throttle position switch harness connector.
2. Check continuity between closed throttle position switch terminals6and5under the following conditions.
SEF330Z
IInsert the 0.05 mm (0.0020 in) and 0.15 mm (0.0059 in) feeler gauge alternately between the stopper and throttle drum
as shown in the figure.
SEF953Y
ªContinuity should existº while inserting 0.05 mm (0.0020 in) feeler gauge.
ªContinuity should not existº while inserting 0.15 mm (0.0059 in) feeler gauge.
OK or NG
OK©GO TO 18.
NG©GO TO 16.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-109