Launch CReader V User Manual page 15

LAUNCH CreaderV User's Manual
Enabling Criteria -- Also termed Enabling Conditions. They are the
vehicle-specific events or conditions that must occur within the engine
before the various monitors will set, or run. Some monitors require the
vehicle to follow a prescribed "drive cycle" routine as part of the enabling
criteria. Drive cycles vary among vehicles and for each monitor in any
particular vehicle.
OBD II Drive Cycle -- A specific mode of vehicle operation that provides
conditions required to set all the readiness monitors applicable to the
vehicle to the "ready" condition. The purpose of completing an OBD II
drive cycle is to force the vehicle to run its onboard diagnostics. Some
form of a drive cycle needs to be performed after DTCs have been
erased from the PCM's memory or after the battery has been
disconnected. Running through a vehicle's complete drive cycle will "set"
the readiness monitors so that future faults can be detected. Drive cycles
vary depending on the vehicle and the monitor that needs to be reset.
For vehicle specific drive cycle, consult the vehicle's Owner's Manual.
Freeze Frame Data -- When an emissions related fault occurs, the OBD
II system not only sets a code but also records a snapshot of the vehicle
operating parameters to help in identifying the problem. This set of
values is referred to as Freeze Frame Data and may include important
engine parameters such as engine RPM, vehicle speed, air flow, engine
load, fuel pressure, fuel trim value, engine coolant temperature, ignition
timing advance, or closed loop status.
Fuel Trim (FT) - Feedback adjustments to the base fuel schedule.
Short-term fuel trim refers to dynamic or instantaneous adjustments.
Long-term fuel trim refers too much more gradual adjustments to the fuel
calibration schedule than short-term trim adjustments. These long-term
adjustments compensate for vehicle differences and gradual changes
that occur over time.
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