I have an 85 coupe and while taking off the upper and lower control arms to redo the suspension noticed a wire was off. This wire was spliced to a black wire that was coming from a sensor on the passenger side of the block between the back two spark plugs. The sensor has a black plug attached to it and two wire coming from it. Again, the black wire coming from the sensor had a piece of wire spliced to it and this wire had a crimp in wire fitting like one you would use to attach to a post or put a screw thru. Is this a ground wire? Any ideas what the sensor is?