Trip Indicators

Trip indicators may be displayed on scan tool. A trip is essential for running the monitors and turning off the MIL. A trip is a set of vehicle operating conditions that must be met for a specified monitor to run. A trip begins with a cycle of ignition key. Trip indicators consist of good trip counters. Good trip counters are: specific good trip, fuel system good trip, misfire good trip and warm-up cycles.

On specific good trips, the term good trip has different meanings. If MIL is off, a trip is defined as when oxygen sensor monitor and catalyst monitor have been completed in the same drive cycle. If MIL is on and a DTC was set by fuel monitor or misfire monitor, the vehicle must be operated in the SIMILAR CONDITIONS WINDOW for a specified amount of time to be considered a good trip. SIMILAR CONDITIONS WINDOW displays information about engine operation during a monitor. If MIL is on and a DTC was set by task manager commanded once per trip monitor such as oxygen sensor monitor, catalyst monitor, purge flow monitor, leak detection pump monitor or oxygen sensor monitor, a good trip is when the monitor passed on next engine start-up. If MIL is on and any other emission related DTC which is not an OBD-II monitor is set, a good trip is considered to be when oxygen sensor monitor or catalyst monitor have been completed, or 2 minutes of engine run times exists and oxygen sensor monitor and catalyst monitor have been stopped from running.

On fuel system good trips, engine must be in closed loop, operating in SIMILAR CONDITIONS WINDOW and short term multiplied by long term must be less than threshold for a predetermined time. SIMILAR CONDITIONS WINDOW displays information about engine operation during a monitor. If all of these conditions exist, PCM will count this as a good trip. Good trip must exist 3 times before MIL will shut off the MIL.

On misfire good trip, vehicle must be operated in the SIMILAR CONDITIONS WINDOW and engine must operate for 1000 revolutions without a misfire. If all of these conditions exist, PCM will count this as a good trip. Good trip must exist 3 times before MIL will shut off the MIL.

On warm-up cycles, once MIL has been turned off by good trip counter, PCM switches to warm-up counter which may be viewed on scan tool. Warm-up cycles are used to erase DTC 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). After 40 warm-up cycles with no malfunction, PCM will erase the DTC.