USER’S MANUAL
OBDII Auto Scanner
8
2.6 OBD II Definitions
Powertrain Control Module (PCM) -- OBDII 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 onboard diagnostic
system can not turn the MIL off until 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 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
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