Chrysler 2005 Crossfire SRT6 Service Manual page 4333

25 - 40 ON-BOARD DIAGNOSTICS
TASK MANAGER
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 40
TASK MANAGER
DESCRIPTION
The PCM is responsible for efficiently coordinating the operation of all the emissions-related components. The PCM
is also responsible for determining if the diagnostic systems are operating properly. The software designed to carry
out these responsibilities is called the Task Manager.
OPERATION - TASK MANAGER
The Task Manager determines which tests happen when and which functions occur when. Many of the diagnostic
steps required by OBD II must be performed under specific operating conditions. The Task Manager software orga-
nizes and prioritizes the diagnostic procedures. The job of the Task Manager is to determine if conditions are appro-
priate for tests to be run, monitor the parameters for a trip for each test, and record the results of the test. Following
are the responsibilities of the Task Manager software:
• Test Sequence
• MIL Illumination
• Diagnostic Trouble Codes (DTCs)
• Trip Indicator
• Freeze Frame Data Storage
• Similar Conditions Window
Test Sequence
In many instances, emissions systems must fail diagnostic tests more than once before the PCM illuminates the
MIL. These tests are know as 'two trip monitors.' Other tests that turn the MIL lamp on after a single failure are
known as 'one trip monitors.' A trip is defined as 'start the vehicle and operate it to meet the criteria necessary to
run the given monitor.'
Many of the diagnostic tests must be performed under certain operating conditions. However, there are times when
tests cannot be run because another test is in progress (Conflict), another test has failed (Pending) or the Task
Manager has set a fault that may cause a failure of the test (Suspend).
• Pending
Under some situations, the Task Manager will not run a monitor if the MIL is illuminated and a fault is stored
from another monitor. In these situations, the Task Manager postpones monitors Pending resolution of the orig-
inal fault. The Task Manager does not run the test until the problem is remedied.
For example, when the MIL is illuminated for an Oxygen Sensor fault, the Task Manager does not run the
Catalyst Monitor until the Oxygen Sensor fault is remedied. Since the Catalyst Monitor is based on signals
from the Oxygen Sensor, running the test would produce inaccurate results.
• Conflict
There are situations when the Task Manager does not run a test if another monitor is in progress. In these
situations, the effects of another monitor running could result in an erroneous failure. If this Conflict is present,
the monitor is not run until the conflicting condition passes. Most likely the monitor will run later after the con-
flicting monitor has passed.
For example, if the Fuel System Monitor is in progress, the Task Manager does not run the EGR Monitor.
Since both tests monitor changes in air/fuel ratio and adaptive fuel compensation, the monitors will conflict with
each other.
• Suspend
Occasionally the Task Manager may not allow a two trip fault to mature. The Task Manager will Suspend the
ON-BOARD DIAGNOSTICS
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OPERATION - TASK MANAGER
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