Chrysler 2005 Crossfire SRT6 Service Manual page 4334

ZH
maturing of a fault if a condition exists that may induce an erroneous failure. This prevents illuminating the MIL
for the wrong fault and allows more precise diagnosis.
For example, if the PCM is storing a one trip fault for the Oxygen Sensor and the EGR monitor, the Task
Manager may still run the EGR Monitor but will suspend the results until the Oxygen Sensor Monitor either
passes or fails. At that point the Task Manager can determine if the EGR system is actually failing or if an
Oxygen Sensor is failing.
MIL Illumination
The PCM Task Manager carries out the illumination of the MIL. The Task Manager triggers MIL illumination upon
test failure, depending on monitor failure criteria.
The Task Manager Screen shows both a Requested MIL state and an Actual MIL state. When the MIL is illuminated
upon completion of a test for a third trip, the Requested MIL state changes to OFF. However, the MIL remains
illuminated until the next key cycle. During the key cycle for the third good trip, the Requested MIL state is OFF,
while the Actual MIL state is ON. After the next key cycle, the MIL is not illuminated and both MIL states read OFF.
Diagnostic Trouble Codes (DTCs)
With OBD II, different DTC faults have different priorities according to regulations. As a result, the priorities deter-
mine MIL illumination and DTC erasure. DTCs are entered according to individual priority. DTCs with a higher pri-
ority overwrite lower priority DTCs.
Priorities
• Priority 0 - Non-emissions related trouble codes
• Priority 1 - One trip failure of a two trip fault for non-fuel system and non-misfire.
• Priority 2 - One trip failure of a two trip fault for fuel system (rich/lean) or misfire.
• Priority 3 - Two trip failure for a non-fuel system and non-misfire or matured one trip comprehensive compo-
nent fault.
• Priority 4 — Two trip failure or matured fault for fuel system (rich/lean) and misfire or one trip catalyst dam-
aging misfire.
Non-emissions related failures have no priority. One trip failures of two trip faults have low priority. Two trip failures
or matured faults have higher priority. One and two trip failures of fuel system and misfire monitor take precedence
over non-fuel system and non-misfire failures.
DTC Self Erasure
With one trip components or systems, the MIL is illuminated upon test failure and DTCs are stored.
Two trip monitors are components requiring failure in two consecutive trips for MIL illumination. Upon failure of the
first test, the Task Manager enters a maturing code. If the component fails the test for a second time the code
matures and a DTC is set.
After three good trips the MIL is extinguished and the Task Manager automatically switches the trip counter to a
warm-up cycle counter. DTCs are automatically erased following 40 warm-up cycles if the component does not fail
again.
For misfire and fuel system monitors, the component must pass the test under a Similar Conditions Window in order
to record a good trip. A Similar Conditions Window is when engine RPM is within ±375 rpm and load is within ±10%
of when the fault occurred.
Note: It is important to understand that a component does not have to fail under a similar window of oper-
ation to mature. It must pass the test under a Similar Conditions Window when it failed to record a Good
Trip for DTC erasure for misfire and fuel system monitors.
DTCs can be erased anytime with a DRB III . Erasing the DTC with the DRB III erases all OBD II information. The
DRB III automatically displays a warning that erasing the DTC will also erase all OBD II monitor data. This includes
all counter information for warm-up cycles, trips and Freeze Frame.
Trip Indicator
The Trip is essential for running monitors and extinguishing the MIL. In OBD II terms, a trip is a set of vehicle
operating conditions that must be met for a specific monitor to run. All trips begin with a key cycle.
ON-BOARD DIAGNOSTICS 25 - 41