The drive cycle is a series of conditions that you drive a vehicle to prepare the emissions systems for an emmisions test.
the drive cycle that is most common to GM vehicles is the following;
1. cold start vehicle and allow to warm up to driving temperature, then set a load on the engine, ie. turn on radio and A/C MAX and headlights.
2. reverse vehicle for approx. 15-20 ft.
3. from a stop, drive vehicle at 35mph @ 25% throttle for 15min
4. allow vehicle to slow to a near stop without using hte brake pedal.
5, begin driving vehivle again 45mph @ 50% throttle for 15-20 min.
6. check for emissions status and test.
***OBDII vehicles (95-99) can have up to (2) two emissions monitors at unready status for PA and can sucessfully submit a "pass" status.
vehicles that are 1988 (OBDI) are emissions exempt.
067 Pa Code 177 204 Basis for failure