8
and go, city type driving, and at least one overnight-off period. For
specific information on getting your vehicle’s OBD II monitor system
ready, please consult your vehicle owner’s manual.
2.6 OBD II Definitions
Powertrain Control Module (PCM)
-- OBD II terminology for the
on-board computer that controls engine and drive train.
Malfunction Indicator Light (MIL)
-- Malfunction Indicator Light
(Service Engine Soon, Check Engine) is a term used for the light on
the instrument panel. It is to alert the driver and/or the repair technician
that there is a problem with one or more of vehicle's systems and may
cause emissions to exceed federal standards. If the MIL illuminates
with a steady light, it indicates that a problem has been detected and
the vehicle should be serviced as soon as possible. Under certain
conditions, the dashboard light will blink or flash. This indicates a
severe problem and flashing is intended to discourage vehicle
operation. The vehicle on-board diagnostic system can not turn the
MIL off until the necessary repairs are completed or the condition no
longer exists.
DTC
-- Diagnostic Trouble Codes (DTC) that identify which section
of the emission control system has malfunctioned.
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
on-board diagnostics. Some form of a drive cycle needs to be
performed after DTCs have been erased from the PCMs memory or
