Trip Indicator

The Trip  is essential for running monitors and extinguishing the MIL. In OBD II terms, a trip is a set of vehicle operating conditions that must be met for a specific monitor to run. All trips begin with a key cycle.

Good Trip 

The Good Trip counters are as follows:

• Specific Good Trip
• Fuel System Good Trip
• Misfire Good Trip
• Alternate Good Trip (appears as a Global Good Trip on DRB III®)
• Warm-up Cycles

Specific Good Trip 

The term Good Trip has different meanings depending on the circumstances:

• If the MIL is OFF, a trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed in the same drive cycle.
• If the MIL is ON and a DTC was set by the Fuel Monitor or Misfire Monitor (both continuous monitors), the vehicle must be operated in the Similar Condition Window for a specified amount of time.
• If the MIL is ON and a DTC was set by a Task Manager commanded once-per-trip monitor (such as the Oxygen Sensor Monitor, Catalyst Monitor, Purge Flow Monitor, Leak Detection Pump Monitor, EGR Monitor or Oxygen Sensor Heater Monitor), a good trip is when the monitor is passed on the next start-up.
• If the MIL is ON and any other emissions DTC was set (not an OBD II monitor), a good trip occurs when the Oxygen Sensor Monitor and Catalyst Monitor have been completed, or two minutes of engine run time if the Oxygen Sensor Monitor and Catalyst Monitor have been stopped from running.

Fuel System Good Trip 

To count a good trip (three required) and turn off the MIL, the following conditions must occur:

• Engine in closed loop
• Operating in Similar Conditions Window
• Short Term multiplied by Long Term less than threshold
• Less than threshold for a predetermined time

If all of the previous criteria are met, the PCM will count a good trip (three required) and turn off the MIL.

Misfire Good Trip 

If the following conditions are met the PCM will count one good trip (three required) in order to turn off the MIL:

• Operating in Similar Condition Window
• 1000 engine revolutions with no misfire

Warm-up Cycles 

Once the MIL has been extinguished by the Good Trip Counter, the PCM automatically switches to a Warm-up Cycle Counter that can be viewed on the DRB III®. Warm-up Cycles are used to erase DTCs and Freeze Frames. Forty Warm-up cycles must occur in order for the PCM to self-erase a DTC and Freeze Frame. A Warm-up Cycle is defined as follows:

• Engine coolant temperature must start below and rise above 71°C (160°F)
• Engine coolant temperature must rise by 4.4°C (40°F)
• No further faults occur