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:

1. Global Good Trip
2. Fuel System Good Trip
3. Misfire Good Trip
4. Alternate Good Trip (appears as a Global Good Trip on scan tool)
   1. Comprehensive Components
   2. Major Monitor
5. Warm-Up Cycles

Global Good Trip 

To increment a Global Good Trip, the Oxygen sensor and Catalyst efficiency monitors must have run and passed, and 2 minutes of engine run time.

Fuel System Good Trip 

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

1. Engine in closed loop
2. Operating in Similar Conditions Window
3. Short Term multiplied by Long Term less than threshold
4. 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:

1. Operating in Similar Condition Window
2. 1000 engine revolutions with no misfire

Alternate Good Trip 

Alternate Good Trips are used in place of Global Good Trips for Comprehensive Components and Major Monitors. If the Task Manager cannot run a Global Good Trip because a component fault is stopping the monitor from running, it will attempt to count an Alternate Good Trip.

The Task Manager counts an Alternate Good Trip for Comprehensive components when the following conditions are met:

1. Two minutes of engine run time, idle or driving
2. No other faults occur

The Task Manager counts an Alternate Good Trip for a Major Monitor when the monitor runs and passes. Only the Major Monitor that failed needs to pass to count an Alternate Good Trip.

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 scan tool. 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:

1. Engine coolant temperature must start below and rise above 160°F (71°C)
2. Engine coolant temperature must rise by 40°F (4.5°C)
3. No further faults occur