R33 Computer (Newb question)

Hello, we've just bought a r33 gts25t, and looked at the main computer. Im not very good with cars nor car electronics (but my family is..lol). When we searched through the car, we found a cable (with no linkage) tucked away, hidden under the passenger mat.

We followed the cable, and opened the covers to reveal the computer. The cable is directly connected into the computer, but leads to nothing. We discovered, strangely enough, the head of the cable is routed back (via adapter) into the computer with a small thin wire.

Usually, i have seen r33 computers with cables wrapped neatly beside it, i've never seen a cable coming out of the computer before (looking like an output)...lol, i've never touched a car's computer before, so the whole story might sound stupid~ sorry ^_^.

Can anyone clear this up for me? what does that cable do? the computer is stock. When I asked a mechanic, they said that it might have been replaced with a aftermarket computer before, then replaced with a stock again when it was sold in Japan.

Thanks.

I know the Catalytic Converter info runs underneath the passenger seat. Check to see if you have one of those. Other than that, i think the information for seatbelts or security sensors might have been plugged in underneath there. Not sure. If you have a CAT and the car works try forget about it. Curiosity is a bitch aint it.

i would say that there used to be an aftermarket piggyback computer of some sort installed, maybe an Apexi RSM or SAFC, but was removed when they sold the car.