Launch CRP123 PLUS - Diagnostic Trouble Codes (Dtcs)

3
LAUNCH
modules to the diagnostic tool.
Monitors -- Monitors are “diagnostic routines” programmed into the PCM. The
PCM utilizes these programs to run diagnostic tests, and to monitor operation
of the vehicle’s emissions-related components or systems to ensure they are
operating correctly and within the vehicle’s manufacturer specications.
Enabling Criteria -- Also termed Enabling Conditions. They are the vehicle-
specic 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. Please refer to the
vehicle’s factory service manual for specic enabling procedures.
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
specic drive cycle, consult the service manual.
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 di󰀨erences and gradual changes that occur over time.
1.4 Diagnostic Trouble Codes (DTCs)
A DTC is a ve digit alphanumeric identier for a fault condition identied by the
OBD II system. There are three types of DTCs:
1.
Pending
– when a fault condition is identied during a Drive Cycle, but does
not meet enough criteria to activate the MIL.
2.
Stored
- A DTC is stored when a fault condition has occurred that meets
enough criteria to activate the MIL.
3.
Permanent
- A stored DTC that can only be cleared by the OBD II system,
after repairs are made, and a set number of Driving Cycles have been
completed.
The rst character, a letter, identies which control system sets the code. The
second character, a number, 0-3; other three characters, a hex character, 0-9
or A-F provide additional information on where the DTC originated and the