Hello all, i installed an engine from the wrecking yard into my dads 2 wheel drive 2001 gmc sonoma (4.3 l vortec) donor motor came from 01 4x4. Cant figure out what this last wire goes to, its 2 wires from the harness, one blue one gray, on the original engine it plugged in on the back of the motor between the oil pressure sending unit and the knock sensor (just under the 2 incoming fuel lines), the 4x4 engine doesnt seem to have that component located there. Any help would be appreciated, thanks.

 

If it is a 4.3 L V6 then the oil press sender and knocksensor are quite a way apart. One on upper rear of block other side of dist. and knock sender on side of block below coolant temp guage sender.
Still unclear on your posting . . .

 

went to the wrecking yard to take a look at another vehicle and realized the plug is missing off my engine. The wires go to a 1 inch by 1/2 inch tall, round, plastic sensor with a hold down bolt right thru the middle of it, the location is between the distributor and the fuel lines coming up to the engine, it is actually mounted onto the top of the trans bell housing. I think it may be some type of magnetic sensor?

 

It has a metal contact patch on its base,it threads into a blind hole on the top of the trans. The "thingy/sensor/or whatever" is made by seimens, without any other part i.d. Its an auto trans also.