1993 2.3 190e Duty Cycle

[denaliano]

I did a quick test today to familiarize myself with measuring duty cycle - as I'm chasing driveablity issues. After reading several threads, I assumed that by connecting my meter leads red - pin 3, black - pin 2 on the capped, round drivers fender mounted port, I'd get some useable numbers.

Key on, engine off, I get 85%. But I do not have a CA car as far as I can tell, only 1 O2 sensor, no LED by the battery...

Also, now I may have connected my leads backwards on my meter. I had to flip them as my first try reading was 15% and that sounded very wrong.

With the car running, it goes to 99.7% or so.

Can someone point me in the right direction here? Being a late model car, I suspect something differs from the typical method of reading it?

I also have a homemade LED/Switch with banana plugs to read codes with, if that's required.