G=
eneral
Motors' OBD-II driving cycle
A complete driving cycle should perform diagnost=
ics on
all systems. A complete driving cycle can be done in un=
der
fifteen minutes.
To perform an OBD-II Driving cycle do the follow=
ing:
1. Cold Start. In order to be classified as a cold start the engine coolant
temperature must be below 50°C (122°F) and within 6°C (11°F=
) of
the ambient air temperature at start-up. Do not leave the key on prior to t=
he
cold start or the heated oxygen sensor diagnostic may not run.
2. Idle. The engine must be run for two and a half minutes with the air
conditioner on and rear defroster on. The more electrical load you can apply
the better. This will test the O2 heater, Passive Air, Purge "No
Flow", Misfire and if closed loop is achieved, Fuel Trim.
3. Accelerate. Turn off the air conditioner and all the other loads and app=
ly
half throttle until 88km/hr (55mph) is reached. During this time the Misfir=
e,
Fuel Trim, and Purge Flow diagnostics will be performed.
4. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes.
During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and F=
uel
Trim diagnostics will be performed.
5. Decelerate. Let off the accelerator pedal. Do not shift or touch the bra=
ke
or clutch. It is important to let the vehicle coast along gradually slowing
down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim
diagnostics will be performed.
6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This
will perform the same diagnostics as in step 3.
7. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minut=
es.
During this time, in addition to the diagnostics performed in step 4, the
catalyst monitor diagnostics will be performed. If the catalyst is marginal=
or
the battery has been disconnected, it may take 5 complete driving cycles to
determine the state of the catalyst.
8. Decelerate. This will perform the same diagnostics as in step 5. Again,
don't press the clutch or brakes or shift gears