meyerld

Hi, my battery failed about a week ago and I replaced it, and reset all the codes. My 03 failed emissions this morning and the tech indicated it needed to be driven to reset the drive cycle on the computer. Any idea how long/many miles is needed to do this? Thanks.

cyclerage23

Get on the highway and speed up to about 55-60, continue for about a mile then stop. Do this 3 to 4 times and this should resent all the monitors in the pcm.

IM QUIKR

I thought it was 40 engine start/stop cylces reset all the PCM info. Now I'm interested.

SFVetteman

Courtesy of forum member Patches:

General Motors OBD-II driving cycle

• 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 the cold start or the heated oxygen sensor diagnostic may not run.

• 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.

• Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.

• 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 Fuel Trim diagnostics will be performed.

• Decelerate. Let off the accelerator pedal. Do not shift or touch the brake 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.

• Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.

• Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. 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.

• Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

dougbfresh

These are called I/M monitors and depending on the state and year of the vehicle not all have to be "READY". Here in Ill, prior ro 2001 I think, you could have 2 MAX-not readys, after that only 1. I seem to recall reading they were going to 0 soon.

John Shiels

took me 25 minutes on a dyno so I could get it inspected.

Blaine 2000 C5

to reset manually:

key on

wait till mssg center done start stuff

press in options and hold

press fuel 4 times

release all.

press reset button

clear yer codes at will read as you go

turn off key

done.

Gordy M

The 40 cycles are for a complete PCM reprogram, including LTFT, etc. The drive cycle will set the I/M settings which are the EPA only pids. Your fuel trims can be +/- 23 percent without throwing a code.