On my 93 4runner 3.0 my check engine light came on, so after running the codes I got code 52 which I believe is a knock sensor but I am not exactly sure, I have no idea where the sensor is thought any opinions would help thanks!

 

The sensor is under the intake plenum.... That being said... usually the problem is the pigtail wire that goes through a notch in the head and comes out under the throttle body. If you remove the rubber hose coming off the t.b. and look back under, you should see the wire and harness coming out from between the plenum, and head, you can unhook the connector, and check for corrosion, and the general health of the wires.
Understand... the code 52 COULD be caused by engine knock... I had the 52 come up on my 93, so I replaced the pigtail, and sensor... still code 52... then re-wired to ecu....still code 52. Not saying this will be your case, usually you just have to replace that pigtail. It is a bit of a job, not too difficult, but one that you do need to pay attention to.