87 gt help

I posted a question yesterday and need to make some changes, the car reads from 8 volts not 0 on the dash I am trouble shooting wires in the car under the dash the previous owner had an alarm in it , wires are spliced, cut, and going god knows where so I am trying to get everything back to the way it was before, If you have any advise for me as far as related issues do to bad wiring please let me know, this is very time cons, any help would be appr...........thanks