The D1 has been throwing code 48 for awhile. I cleaned the stepper motor , cleared the code and a few weeks later the CEL is on and code 48 is back. The truck runs fine so this is must be a minor hiccup. I want to check the base idle before condemning the stepper and read some instructions on how to do this from a previous post but at the risk of sounding stupid.......... where is the idle speed screw located? 