i have a 1990 chevrolet cheyenne 4x4 reg cab long bet with a 350, th400 automatic and i when i bought it my oxygen sensor wire was jurked loose and i need to know where to hook it up at?

 

I,m not sure which one you have but I am going to assume it is a single wire that goes into the manifold. If so you should have one on each side of the engine. You will just have to look for a wire hanging to plug it into. Does it have a wire coming off the sensor? If it got ripped off you will need a new sensor. The wire on the harness will more than likely be hanging somewhere between the sensor and the firewall. It should be the only wire that will plug into the sensor.
If you have a heated sensor you will have 4 they have a 4 wire plug. 1 in front of each cat and one behind. The harness should have a clip that holds the wires to the frame or something close to the sensors.
Good luck.

 

its a 1 wire and the connectors are ripped off of it but the wire is still connected to the o2 sensor and i found a wire on the firewall coming out behind the throttlebody that wiil reach it could this be it and what will it do if i leave it unplugged