8
OBDII Drive Cycle
:
A specific mode of vehicle operation that provides condition 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 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
vehicle's Owner's Manual.
OBDII Monitor Readiness Status
OBDII systems must indicate whether or not the vehicle's PCM monitor system has completed
testing on each component.
Recording readiness allows inspectors to determine whether all
components or systems have been tested. Tested components will be reported as 'Ready' or
'Complete'.
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 scan tool 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 start, 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
vehicles Owner’s Manual.
