Buick Regal Knock sensor wire

Hi can anyone tell me where the wire from the knock sensor goes. I have a 1992 Buick regal v6 and the wire seems to be missing, all I have on the sensor was a plug. I bought a new pigtail for it but I cant seem to find the broken wire so I fugured If I knew where it went I would just try to splice in there. I guess I would probally be able to find the wire if i where able to get in between the engine and the firewall but as you know the space is very limited. Thanks hope to hear from someone soon.