I installed a Blaupunkt mp3000 in my 96 C280. Bought the radio with harness adaptor from crutchfield. I have two problems. 1: there is a constant hissing in the background which does not get louder with volume. When volume is at 0 there is none, when volume is at one or higher the hissing is present. 2: When I turn off power to the car the radio losses all memory settings and sets back to default settings. Does anyone know where I can get a wiring diagram for the c280 so I can be sure my wire connections are correct? Is there something else I should know? Why is there an extra set of plugs that does not plug in to the adaptor for the radio?