Oil Light is ON when engin is turned off

Hi , My engin oil light stay ON when I turn the engin off. When I turn the switch to ON then it almost turned off with a small light showing.

What I did recently is installing a radio, and connected the memory wire of the radio to a wire under the dash that was 12v all the time. This cause my engin to run very poor, then car light start flashing and big noice, I burned a 30A fuse on the main line from battery to the relay. So I disconnect the radio and now the Oile light is ON all the time. Any help appriciated.

Well the dam new chrome alternator was the main problem. It had a short and it was causing all the issues as the oil light and many other issues. I put my old Alternator and all the electrical problems are gone. I bough this new chrome alternator from LA classis car show in Fairplex. So I cannot return it, since they do not give you a receit and the show will come in 2 or 3 months. So my advisee to every one, BECAREFULL when you buy electronic items from a car show. ;) :)