Need help locating the reverse gear signal input on 92 Teg!

I need to locate the Reverse Signal Input on my 92 Integra (LS) for use with the GPS on a new in-dash I bought. On a side note I just finished installing a new system along with the in-dash but I keep getting some audio interference, but only when the kicker is connected. It seems to pick up all of the vibrations in the car or so it sounds like it does, any suggestion. I have never had this issue before with the car.

Thanks for your time!!!