OBD II DRIVE CYCLES

For a system that is supposed to be standardized OBD II drive cycles are not. For what ever reason, each vehicle manufacturer came up with their own unique drive cycles that must be followed before certain OBD II monitors will run their self checks.

The toughest monitors to set are the catalyst monitor and the EVAP monitor because these two monitors typically require the most complicated drive cycles.

Because there are so many different makes and model of vehicles, we cannot include all of the individual drive cycles in this reference program.

For vehicle specific details, you should consult the OEM service literature or applicable technical service bulletins.

Many drive traces have "prerequisites" (conditions that must exist) before they will run or set a diagnostic trouble code.

The ambient temperature may have to be above a certain degree, or the vehicle may have had to sit for a certain period of time since it was last driven.

For example, some vehicle manufacturers require an eight hour cold soak period before it will run the EVAP monitor.

The PCM has a timer that keeps track of how long the vehicle has sit since it was last driven.

If it hasn't been a full eight hours, the EVAP monitor won't run until the required time period has passed.

DRIVING TIPS

Test driving a vehicle in an attempt to get all the monitors to run is best done with two people: one to drive and one to check the readiness status on a scan tool.

Don't try to drive and read a scan tool at the same time or you may find yourself making an unplanned trip to an emergency room.

As a rule, driving on flat terrain will set the monitors more quickly than driving on hilly terrain.

You should also accelerate gradually rather than flooring the throttle, and brake smoothly (don't slam on the brakes).

Aggressive driving won't speed up the process and may actually delay the setting of some monitors. It takes time so be patient.

If you are having problems getting a monitor to run, remember that some monitors are load sensitive.

Shifting to a lower gear or disengaging overdrive may reduce the load just enough so the monitor will run.

Extreme ambient temperatures (100 degrees F or higher) may also inhibit some monitors from running. Your only option here is wait until the weather cools to run your drive cycle.

If a front-wheel drive or rear-wheel drive vehicle is being run on a dyno or road simulator, follow all the usual safety precautions such as making sure the vehicle is properly tethered or chained down, the parking brake is set (front-wheel drive only), the non-drive wheels are chocked, and no one is standing in front of the vehicle.

A floor fan may also be required to help cool the radiator for sustained high speed operation.

Note: Four-wheel drive (4WD) vehicles and All-Wheel Drive (AWD) vehicles cannot be run on a dyno unless they can be operated in a two-wheel drive mode.

UNIVERSAL DRIVE CYCLE

There's really no such thing as a universal drive trace that works for all vehicles, but this one may work if you don't have the official OEM drive cycle:

1. Start the vehicle and wait until the engine has come to normal operating temperature before you start your test drive.
   
2. Find a flat, straight section of road and drive the vehicle 45 mph for about 10 seconds, then gradually slow down to about 30 mph for 10 seconds, then gradually accelerate back up to 45 mph. Repeat this cycle ten times.
   
3. After the last cycle, cruise at a steady speed of about 40 mph for about 1 minute, then accelerate quickly up to 55 mph and hold at 55 mph for about 3 minutes. 45 mph. The total test drive should take at least 12 to 15 minutes.

Check if your car manufacturer is included in our Drive Cycle database.