Description of Drive Cycles

TRIP

Purpose
Trip is a drive cycle with specific instructions for vehicle operation within a period of time. During a Trip, all On-Board Diagnostics II (OBD II) components and monitors (except the Catalyst Efficiency Monitor) are tested at least once by the on-board diagnostic system. This testing detects irregularities preventing a vehicle from meeting emission requirements.

Operation
Trips are used by the software strategy to control the Malfunction Indicator Lamp (MIL) "OFF" function. The MIL is turned "OFF" if there are three consecutive drive cycles without the identical fault under similar conditions or three Trips without the identical fault present. The actual number of Trips or drive cycles necessary to control the MIL varies with each monitor.

DRIVE CYCLE

Purpose
A drive cycle is a method of driving a vehicle to verify a driveablity symptom or its repair. It can also be a method of driving a vehicle to begin and complete a specific OBD II monitor or Trip. A drive cycle may require specific drive modes such as:
- Number of idle periods
- Steady vehicle speed per time
- Accelerations at certain throttle angles, etc.

OBD II DRIVE CYCLE

Purpose
THE OBD II Drive Cycle is a specific method used to perform all Trip monitor tests, including the Catalyst Efficiency Monitor Test.

Drive Instructions:

The following conditions must occur to complete a Trip and test all OBD II monitors and components including the Catalyst Efficiency Monitor:

- The Misfire, Comprehensive Component and Adaptive Fuel Monitors are checked continuously from engine warm-up and can complete any time.

- The Exhaust Gas Recirculation (EGR) Monitor test requires a series of idles and accelerations.

- The Heated Oxygen Sensor (HO2S) Monitor requires a steady speed drive for a period of time at 30 to 40 mph.

- The Catalyst Efficiency Monitor requires a steady speed drive for an additional 80 seconds beyond the HO2S Monitor test at 40 to 65 mph.