Infiniti Q45 (FY33). Manual — part 139
SEF720X
SEF139P
Generic Scan Tool (GST)
DESCRIPTION
Generic 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 “GST” or “Generic Scan Tool” is used in this service
manual.
SEF046TA
GST INSPECTION PROCEDURE
1.
Turn off ignition switch.
2.
Connect “GST” to data link connector which is located under
LH dash panel near the hood lock release handle.
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont’d)
EC-85
SEF398S
3.
Turn ON ignition switch.
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.
FUNCTION
Diagnostic test mode
Function
MODE 1
READINESS TESTS
This mode gains access to current emission-related data values, including analog
inputs and outputs, digital inputs and outputs, and system status information.
MODE 2
(FREEZE DATA)
This mode gains access to emission-related data value which were stored by ECM
during the freeze frame. [For details, refer to “Freeze Frame Data” (EC-77).]
MODE 3
DTCs
This mode gains access to emission-related power train trouble codes which were
stored by ECM.
MODE 4
CLEAR DIAG INFO
This mode can clear all emission-related diagnostic information. This includes:
I
Clear number of diagnostic trouble codes (MODE 1)
I
Clear diagnostic trouble codes (MODE 3)
I
Clear trouble code for freeze frame data (MODE 1)
I
Clear freeze frame data (MODE 2)
I
Reset status of system monitoring test (MODE 1)
I
Clear on board monitoring test results (MODE 6 and 7)
MODE 6
(ON BOARD TESTS)
This mode accesses the results of on board diagnostic monitoring tests of specific
components/systems that are not continuously monitored.
MODE 7
(ON BOARD TESTS)
This mode enables the off board test drive to obtain test results for emission-related
powertrain components/systems that are continuously monitored during normal driv-
ing conditions.
MODE 8
—
This mode can close EVAP system in ignition switch “ON” position (Engine stopped).
When this mode is performed, the following parts can be opened or closed.
I
EVAP canister vent control open
I
Vacuum cut valve bypass valve closed
In the following conditions, this mode cannot function.
I
Low ambient temperature
I
Low battery voltage
I
Engine running
I
Ignition switch “OFF”
I
Low fuel temperature
I
Too much pressure is applied to EVAP system
MODE 9
(CALIBRATION ID)
This mode enables the off-board test device to request specific vehicle information
such as Vehicle Identification Number (VIN) and Calibration IDs.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Generic Scan Tool (GST) (Cont’d)
EC-86
MEF036D
SEF233G
SEF234G
Introduction
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 “Work Flow” on EC-89.
Before undertaking actual checks, take just a few minutes to talk
with a customer who approaches with a driveability complaint. The
customer can supply good information about such problems, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A “Diagnostic Worksheet” like the
example below should be used.
Start your diagnosis by looking for “conventional” problems first.
This will help troubleshoot driveability problems on an electronically
controlled engine vehicle.
SEF907L
Diagnostic Worksheet
There are many operating conditions that lead to the malfunctions
of engine components. A good knowledge of such conditions can
make troubleshooting faster and more accurate.
In general, each customer may feel differently about a given prob-
lem. It is important to fully understand the symptoms or conditions
for a customer complaint.
Utilize a diagnostic worksheet like the one shown below in order to
organize all the information for troubleshooting.
Some conditions may cause the malfunction indicator lamp to
come on steady or blink and DTC to be detected. Examples:
I
Vehicle ran out of fuel, which caused engine misfire.
I
Fuel filler cap was left off or incorrectly screwed on, allowing
fuel to evaporate into the atmosphere [for models with EVAP
(SMALL LEAK)] diagnosis.
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TROUBLE DIAGNOSIS — Introduction
EC-87
WORKSHEET SAMPLE
Customer name
MR/MS
Model & Year
VIN
Engine #
Trans.
Mileage
Incident Date
Manuf. Date
In Service Date
Fuel and fuel filler cap
l
Vehicle ran out of fuel causing misfire.
l
Fuel filler cap was left off or incorrectly screwed on.
Symptoms
l
Startability
l
Impossible to start
l
No combustion
l
Partial combustion
l
Partial combustion affected by throttle position
l
Partial combustion NOT affected by throttle position
l
Possible but hard to start
l
Others [
]
l
Idling
l
No fast idle
l
Unstable
l
High idle
l
Low idle
l
Others [
]
l
Driveability
l
Stumble
l
Surge
l
Knock
l
Lack of power
l
Intake backfire
l
Exhaust backfire
l
Others [
]
l
Engine stall
l
At the time of start
l
While idling
l
While accelerating
l
While decelerating
l
Just after stopping
l
While loading
Incident occurrence
l
Just after delivery
l
Recently
l
In the morning
l
At night
l
In the daytime
Frequency
l
All the time
l
Under certain conditions
l
Sometimes
Weather conditions
l
Not affected
Weather
l
Fine
l
Raining
l
Snowing
l
Others [
]
Temperature
l
Hot
l
Warm
l
Cool
l
Cold
l
Humid
°F
Engine conditions
l
Cold
l
During warm-up
l
After warm-up
Engine speed
Road conditions
l
In town
l
In suburbs
l
Highway
l
Off road (up/down)
Driving conditions
l
Not affected
l
At starting
l
While idling
l
At racing
l
While accelerating
l
While cruising
l
While decelerating
l
While turning (RH/LH)
Vehicle speed
Malfunction indicator lamp
l
Turned on
l
Not turned on
TROUBLE DIAGNOSIS — Introduction
Diagnostic Worksheet (Cont’d)
EC-88
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