Disconnecting Battery

No it is not neccessary and yes chances are you wired it wrong.Certified Security Specialist

Always check info with a digital multimeter.

I promise to be good.

Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

i would still suggest that you do pull it off though. it really sucks to short a wire. explain how you installed the deck and we can help you. car info and deck info too

well i installed a aiwa mp3 cd reciever in my 1995 hyundai scoupe. i wired everything in a harness and what not and the problem seems to be with the red(power) and yellow(battery) wires. when i attach them togather seperately the radio does not function. but i attacked all 4 togather and it works but when you shut off the car it resets to factory settings...i dono..help thanks

Where did you ground the radio at? Some of the old hyunday's (don't care) are common ground as well.Certified Security Specialist

Always check info with a digital multimeter.

I promise to be good.

Tell Darwin I sent you.

I've been sick lately, sorry I won't be on much.

If the radio resest after you turn the car off, then you don't have a constant 12v.  Use a Multi Meter to double check all the wires in the harness are the correct ones. Double check your fuses as well.