got a digital multimeter(generic for 4$!, same as the motorcraft that is 20$), got wiring diagrams from haynes and autozone.com but i don't know what terminals "A and B" are as said on the link u gave me. also , i have no experience with electronics other than building and troubleshooting computers. so how do you "backprobe" connectors and what is required to do so? is it safe to use my 10A multimeter with battery connected? don't wanna blow the fuse or myself up! LOL! according to the wiring diagram, 24x sensor has 2 red and 1 yellow/blue - but not sure which is which.. ergh, o , and one more thing, when they say crank the engine, do they mean manually or by starting the car? thanx