Trip Indicator

The trip is essential for running monitors and turning off the Malfunction Indicator Light (MIL). A trip is defined as a set of vehicle operating conditions that must be met for a monitor to run. All trips begin with an ignition key cycle. Good trip counters are: good trip, fuel system good trip and misfire good trip.

• Specific Good Trip
  
  The term good trip has different meanings depending on the circumstances. If the MIL is off, a good trip is defined as when the oxygen sensor monitor and the catalyst monitor have completed in the same drive cycle. If the MIL is on and a DTC was set by the fuel system monitor or misfire monitor, vehicle must be operated in the similar conditions window for a specified amount of time. If MIL is on and a DTC was set by a PCM task manager commanded once-per-trip monitor (oxygen sensor/heater monitor, catalyst monitor, purge flow monitor, leak detection monitor or EGR monitor), a good trip is when the monitor is passed on the next engine start-up. If the MIL is on and any other emissions DTC is set (not an OBD-II monitor), a good trip is when the oxygen sensor monitor and catalyst monitor have completed, or 2 minutes of engine run time has occurred (if the oxygen sensor monitor and catalyst monitor has stopped running).
  NOTE: For more information on similar conditions window, see SIMILAR CONDITIONS WINDOW  .
• Fuel System Good Trip
  
  To count a good trip (3 required) and turn off the MIL, the following conditions must be met. Engine must be in closed loop, must be operating in similar conditions window and short term multiplied by long term must be less than threshold value.
• Misfire Good Trip
  
  If operating in similar conditions window and 1000 engine revolutions have occurred with no misfires, the PCM will count one good trip (3 required) in order to turn off MIL.
• Warm-Up Cycles
  
  Once the MIL has been turned off by the good trip counter, the PCM will automatically switch to a warm-up cycle counter that can be viewed by the DRBIII(R) scan tool. Warm-up cycles are used to clear DTCs and freeze frame data from PCM memory. Forty warm-up cycles are necessary to clear DTCS and freeze frame data. A warm-up cycle is defined as the engine is started, an increase of 40°F (4°C) in engine coolant temperature exists after engine is started and engine coolant temperature reaches at least 160°F (71°C).