Trips and Drive Cycles

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
- Adaptive Fuel Monitor and
- Secondary Air Injection Monitor

The Catalyst Efficiency Monitor is a steady-state monitoring system and is not part of a Trip.

TRIP DISPLAY on SCAN TOOL
The On-Board System Readiness function will be available on all scan tools. This function will indicate the status of each OBD II monitor. One Parameter Identification (PID) display on a New Generation STAR (NGS) summarizes the status of all monitors for a TRIP SET as Yes or No.

NOTE: A Trip must be completed to establish entry conditions necessary for the monitoring of the Catalyst Efficiency Monitor test.

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 OFF if there are three consecutive drive cycles without the identical fault present. The actual number of drive cycles or Trips necessary to control the MIL varies with each monitor.

TRIPS AND DIAGNOSTIC TROUBLE CODES
A DTC will be stored the in memory after the identical malfunction has been detected consecutively on at least two separate drive cycles (not necessarily completing a Trip). A Misfire Monitor DTC can be stored immediately depending on misfire type. A Catalyst Efficiency Monitor DTC can be stored after three identical malfunctions are detected on three separate drive cycles. A DTC will be erased from memory after 40 engine warm-up cycles if the malfunction has not been detected after the MIL is turned OFF. DTC memory storage requirements vary with each monitor.

Drive Instructions:

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.

TRIP MONITOR AND CATALYST EFFICIENCY MONITOR (OBD II DRIVE CYCLE) REQUIREMENTS
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 anytime.
- The EGR Monitor test requires a series of idles and accelerations.
- The HO2S Monitor requires a steady speed drive for approximately 1 minute at 30 to 40 mph.
- The Secondary Air Injection Monitor requires more than 10 minutes of vehicle operating time from initial start-up.
- The Catalyst Efficiency Monitor requires a steady speed drive for 1 minute and 20 seconds beyond the HO2S Monitor test at 40 to 65 mph.