Hi Mike , our cars do have the OBD I and the duty cycle meter is necessary to diagnose certain conditions . It reads in percent and you compare that to normal (anyone who actually understands this stuff can jump right in
). I checked my DMM and it doesn't read duty cycle but it has more features overall than the Sears model. I'm going to check my local Sears for the model mentioned in the other thread.
Click here for a link to a thread about the duty cycle.