So about 6 months ago I purchased a 93 Sc400 and take been sitting ever since because I had to wait until I could obtain my driver's license and I recently through some gas in it and a new battery and started to diagnose what's wrong and there is alot, My gas gauge doesn't work, and the needles also do not work in the dash, my Steering Wheel tilter doesn't work, my done light do not work my trunk does not shut without using the driver lock button, and my radio does not work it is after market so that could be the problem and I've checked the fuses to see if there were there which both of them are so if anyone could assist me I would be thankful for, Thank You

 

You've got some work ahead of you - I have a 93 with electrical problems as well
Right off, these wonderful cars of ours have some inherent problems:
1 - the engine harness came from the fcty with a design flaw that can wreak havoc on these cars, it was mounted on (aka - weaved into) the engine and will suffer from heat issues melting wires the moment the engine runs a little hot (if I ever meet that engineer...)
2 - there are many electrical modules throughout the car that have capacitors that were only designed to last 14yrs - the ECM, radio, ac controls, gauges, fuel pump module, etc, etc will (most likely) all need to be refurbished or replaced
3 - due to age, grounds become an issue - and there are many....all over....inside and out

The best I can suggest is find experienced and willing help - I only visit in Fla but there are some owners in and around Tampa/Orlando area (mid state) and one SC outfit on FB (https://www.facebook.com/SCFactory/) that may can help - they are doing ECM repairs now
I'd be glad to answer questions if I can, feel free to ask

 

thank You So Much, Ill try out the facebook page