Drive Cycles and Trips

DRIVE CYCLE
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 initiate and complete a specific OBD II monitor or trip. A drive cycle may be done in the service bay, or may require specific drive modes such as a number of idle periods, steady vehicle speed for a specified amount of time, accelerations at certain throttle angles, etc.

OBD II DRIVE CYCLE
The OBD II drive cycle is a specific method used to perform all trip monitor tests, as well as the catalyst efficiency monitor test. Monitors, Trips, Drive Cycles and Readiness Codes

TRIP
A trip is a drive cycle with specific instructions for vehicle operation within a period of time. During a trip, all OBD II components and monitors (except the catalyst efficiency monitor) are tested at least once by the on board diagnostics system. This testing detects irregularities preventing a vehicle from meeting emission requirements.

The system monitors included in a trip are:
- Comprehensive component monitor
- Misfire detection monitor
- Exhaust Gas Recirculation (EGR) System monitor
- Heated oxygen sensor monitor
- Oxygen sensor heater
- Catalyst efficiency monitor

TRIPS AND MALFUNCTION INDICATOR LAMP FUNCTION
Trips are used by the software strategy, internal to the Powertrain Control Module (PCM), to control Malfunction Indicator Lamp (MIL) operation. The MIL is turned ON after the same malfunction has been detected for two consecutive drive cycles, with the exception of the misfire Diagnostic Trouble Codes (DTCs). If a misfire is detected that may cause damage to the catalytic convertor(s), the MIL will be turned ON at the first event, and may flash to warn the driver of potential catalyst damage. The MIL is turned OFF if, after three consecutive drive cycles, the same malfunction is not detected.

TRIPS AND DIAGNOSTIC TROUBLE CODES
A DTC will be stored the first time a malfunction is detected, even if the MIL is not illuminated. The DTC will remain in Keep Alive Memory (KAM) until the DTC is cleared, or until 40 warm-up cycles have been completed without the same malfunction being detected after the MIL has turned OFF. The DTC will also be cleared from KAM in the event that power is lost to the PCM including disconnecting the battery or the PCM vehicle harness connectors.