Idiomas disponibles
Idiomas disponibles
Once the vehicle is running, the OBDII system is continuously checking the above
components, monitoring key engine sensors, watching for engine misfire, and monitoring
fuel demands.
Non-Continuous Monitors -- - Unlike the continuous monitors, many emissions and engine
system components require the vehicle to be operated under specific conditions before the
monitor is ready. These monitors are termed noncontinuous monitors and are listed below:
1) EGR System
2) O2 Sensors
3) Catalyst
4) Evaporative System
5) O2 Sensor Heater
6) Secondary air Injection
7) Heated Catalyst
8) A/C system
2.5 OBDII Monitor Readiness Status
OBDII systems must indicate whether or not the vehicle's PCM's monitor system has
completed testing on each component. Components that have been tested will be reported
as "Ready", or "Complete", meaning they have been tested by the OBDII system.
The purpose of recording readiness status is to allow inspectors to determine if the
vehicle's OBDII system has tested all the components and/or systems. The Powertrain
Control Module (PCM) sets a monitor to "Ready" or "Complete" after an appropriate drive
cycle has been performed. The drive cycle that enables a monitor and sets readiness
codes to "Ready" varies for each individual monitor. Once a monitor is set as "Ready"
or "Complete", it will remain in this state. A number of factors, including erasing of
Diagnostic Trouble Codes (DTCs) with a code reader or a disconnected battery, can result
in Readiness Monitors being set to "Not Ready". Since the three continuous monitors
are constantly evaluating, they will be reported as "Ready" all of the time. If testing of a
particular supported non-continuous monitor has not been completed, the monitor status
will be reported as "Not Complete" or "Not Ready."
In order for the OBD monitor system to become ready, the vehicle should be driven under
a variety of normal operating conditions. These operating conditions may include a mix of
highway driving and stop and go, city type driving, and at least one overnight-off period.
For specific information on getting your vehicle's OBD monitor system ready, please
consult your vehicle owner's manual.
7
www.mucarco.com
www.mucarco.com
2.6 OBDII 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 cannot turn the MIL off until the necessary repairs are
completed or the condition no longer exists.
DTC -- Diagnostic Trouble Codes (DTC) that identifies which section of the emission
control system has malfunctioned.
Enabling Criteria -- Also termed Enabling Conditions. They are the vehiclespecific 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 specific enabling
procedures.
OBDII 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 OBDII 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 OBDII 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
8
