OBD II Basics

[IgotTwo]

I used my OBDII code scanner for the first time and surprised myself my pulling off the quick codes with great ease (key on engine off )

I’m going up the learning curve and I’m in front my headlights on this. So before I hurt myself and others, I’m trying to tie some loose ends of my understanding together .
One thing I did find is the Ford Driving Cycling for OBDII. This appears to be pretty rigorous, but clearly, intended to check all aspects of the vehicle.

I’m not sure if this is a fair question, but, is it always necessary to go through the entire cycle? By way of example, am I missing the whole concepts by assuming that you can “check” some systems and get valid output at idle and it is not always necessary to go through the complete driving cycle?

If anyone can point me to some good reference books or material on ODBII, that would also be greatly appreciated.


Did I miss the comments about the mods to the site?
They're nice!!! Excuse me!! Damn Nice!!!!
(more manly)
Good going guys

 

[Robert]

You do not need to do a complete driving cycle to trouble shoot most problems. A complete driving cycle will be automatically completed once the necessary steps have gone through. A few days of ordinary driving is usually enough to complete it. Your scanner should tell you if the drive cycle (otherwise known as OBD-II Trip has been completed or not. My scanner will still pull the codes and go through most test even if it hasn't been completed. I don't think I can do the O2 sensor tests on mine before the OBD-II trip has been completed but I can't remember any others. Before disconnecting the battery (which will clear the driving cycle from memory, run the tests. If it doesn't get you anywhere, then disconnect the battery to clear the driving cycle from memory. I can't remember if using my scanner to clear all codes resets it. Drive it for a day or two until the driving cycle has been completed. One instance where I can see this being of use would be when troubleshooting an O2 problem. Your PCM will store both short-term and long-term O2 trims for both banks. Short-term is an instant snapshot. Long-term is the average over a long time so if your vehicle has been running fine for a long time, but only recently started running rich or lean then by clearing the drive cycle and then checking things out after a couple of days would give your a two day snap shot for your long-term fuel trims.

 

[IgotTwo]

Robert
thanks for good pointers
helped my comfort level alot....I think I heard a "base line file" is a good thing to have on hand.
Before and after snap spots sound good to me too.
Lot to learn
Thanks again