6E–40
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Information
The diagnostic charts and functional checks are designed
to locate a faulty circuit or component through a process
of logical decisions. The charts are prepared with the
requirement that the vehicle functioned correctly at the
time of assembly and that there are no multiple faults
present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunction
is a system of diagnostic trouble codes. When a
malfunction is detected by the control module, a
diagnostic trouble code is set and the Malfunction
Indicator Lamp (MIL) (“Check Engine” lamp) is
illuminated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with (“Check Engine”
lamp). However, OBD II requires that it illuminate under a
strict set of guide lines.
Basically, the MIL is turned on when the PCM detects a
DTC that will impact vehicle emissions.
The MIL is under the control of the Diagnostic Executive.
The MIL will be turned on if an emissions-related
diagnostic test indicates a malfunction has occurred. It
will stay on until the system or component passes the
same test, for three consecutive trips, with no emissions
related faults.
If the vehicle is experiencing a misfire malfunction which
may cause damage to the Three-Way Catalytic
Converter (TWC), the MIL will flash once per second.
This will continue until the vehicle is outside of speed and
load conditions which could cause possible catalyst
damage, and the MIL will stop flashing and remain on
steady.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn off
the MIL after
three(3) consecutive trips that a “test
passed” has been reported for the diagnostic test that
originally caused the MIL to illuminate.
Although the MIL has been turned off, the DTC will remain
in the PCM memory (both Freeze Frame and Failure
Records) until
forty(40) warm-up cycles after no faults
have been completed.
If the MIL was set by either a fuel trim or misfire-related
DTC, additional requirements must be met. In addition to
the requirements stated in the previous paragraph, these
requirements are as follows:
D
The diagnostic tests that are passed must occur
within 375 RPM of the RPM data stored at the time the
last test failed.
D
Plus or minus ten (10) percent of the engine load that
was stored at the time the last failed.
D
Similar engine temperature conditions (warmed up or
warming up ) as those stored at the time the last test
failed.
Meeting these requirements ensures that the fault which
turned on the MIL has been corrected.
The MIL (“Check Engine” lamp) is on the instrument
panel and has the following function:
D
It informs the driver that a fault affects vehicle
emission levels has occurred and that the vehicle
should be taken for service as soon as possible.
D
As a bulb and system check, the MIL will come “ON”
with the key “ON” and the engine not running. When
the engine is started, the MIL will turn “OFF.”
D
When the MIL remains “ON” while the engine is
running, or when a malfunction is suspected due to a
driveability or emissions problem, a Powertrain
On-Board Diagnostic (OBD ll) System Check must be
performed. The procedures for these checks are
given in On-Board Diagnostic (OBD) System Check.
These checks will expose faults which may not be
detected if other diagnostics are performed first.
DTC Types
Each DTC is directly related to a diagnostic test. The
Diagnostic Management System sets DTC based on the
failure of the tests during a trip or trips. Certain tests must
fail two (2) consecutive trips before the DTC is set. The
following are the four (4) types of DTCs and the
characteristics of those codes:
D
Type A
D
Emissions related
D
Requests illumination of the MIL of the first trip with a
fail
D
Stores a History DTC on the first trip with a fail
D
Stores a Freeze Frame (if empty)
D
Stores a Fail Record
D
Updates the Fail Record each time the diagnostic
test fails
D
Type B
D
Emissions related
D
“Armed” after one (1) trip with a fail
D
“Disarmed” after one (1) trip with a pass
D
Requests illumination of the MIL on the
second
consecutive trip with a fail
D
Stores a History DTC on the second consecutive trip
with a fail (The DTC will be armed after the first fail)
D
Stores a Freeze Frame on the second consecutive
trip with a fail (if empty)
D
Stores a Fail Record when the first test fails (not
dependent on
consecutive trip fails)
D
Updates the Fail Record each time the diagnostic
test fails
(Some special conditions apply to misfire and fuel trim
DTCs)
D
Type C (if the vehicle is so equipped)
D
Non-Emissions related
D
Requests illumination of the Service
D
Stores a History DTC on the
first trip with a fail
D
Does not store a Freeze Frame
D
Stores Fail Record when test fails
D
Updates the Fail Record each time the diagnostic
test fails
D
Type D
D
Non-Emissions related