I installed a pioneer radio in my 02 slk32. Everytime i start the car the radio resets to 12 and i have to go through the setup process again. I checked the constant and switched 12v power going to the radio. The switched works as it should, the constant drops from 12v to about 3v over the period of about a minute once the key has been removed from the ignition. If you open the driver door the constant goes to 12v again, close it and it drops to 3v. I did some research on this already some people say to swap the constant and switched power on the aftermarket radio harness but obviously that wouldnt work in this situation, some also say tap into the cigarette lighter for constant 12v but the cigrette lighter only gets power when the key is on. Is there something wrong or do i have to find another constant 12v source.