Launch Creader PROFESSIONAL 129 EVO User Manual page 12

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Creader Professional 129 EVO / EVO+
specific enabling procedures.
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 service
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 to
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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