Specific GM OBDII Driving Cycle

[JimD]

My faithful '98 failed the 'OBD Readiness' test twice this week. And it was because I had recently cleared all the codes (chasing a nuisance "B" code) and I had disconnected the battery for some routine cable end inspecting / cleaning.

There were no "P" codes set and the Service Engine Soon message was not displayed.

Hello Google; too much information! Two of the Google results just made the most sense because they both mentioned GM specific driving cycles to establish the OBD Readiness flags as good-to-go.

You can fail the emissions test if the OBD is not ready and nothing else is wrong.

[GreenMachine]

Yeah, be nice if the inspection was based on actual tail pipe emmisions and safety related things on the car (brake lines, fuel lines etc.)

[JimD]

Just to clarify, I followed the instructions on the "Illinois" page in the first post to the letter with a stop-watch. Performing the drive cycle did the trick; all the readiness flags were set to green and the car passed the test.

[Logan]

We came up with the dream....

You could make a living standing in the state emissions test line with a GM Tech 2.

Aahhh, not so fast grasshopper. Need 2-3 days driving to get those readiness programs to do their thing.

Maybe next time....

[nigel]

do those drive cycles have to be performed to the letter or is that a precis of a 2-3 day normal cycle?

here in the UK at our annual government test (MOT) we have tail pipe emissions, they check at idle and if your car was built after 1992 they check the operation of the cat at 3000rpm. the check takes about 3 minutes and most testers know a few tricks to get borderline motors to pass.

the rest of the test is on items of safety and is open to the testers interpretation of the regulations.

they test lights, seats and belts, structural integrity, steering, tyres, suspension, fuel tank and lines and worst of all they use a rolling road to test the brakes, checking for left-right balance, actual stopping force (the brakes must be able to produce a stopping force on the rollers measured in kilos), and the parking brake.

the parking brake must operate at a minimum of 16% of the cars total weight. trying to get a 1970's cadillac or olds to put an equal force on each parking brake is almost impossible.

curse you unequal length brake cables.

[JimD]

The drive cycle would happen under normal driving circumstances. In my case, I had done some repairs and not enough time / distance had accumulated before I took the car to the inspection facility.

Over here, safety inspections are not required in any areas that I am personally aware of. The condition of my tires and brakes would become an issue if I was involved in a wreck.

Inspections for tailpipe emissions can be and are required in high population density centers and in some cases, on a state-wide basis. Comparing the population density (and consequently vehicle density) of New Jersey to that of Wyoming tells the tale.

I live in one of the Georgia counties that falls under a federal EPA mandate that requires annual emissions inspections. For cars manufactured after 1996, the inspection consists of plugging into the OBDII data port and reading the information. The absence of emissions related powertrain codes is de facto evidence the test has been passed.