Thinkcar THINKTOOL Manual Del Usuario página 14

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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
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
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
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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