I just installed a new cheap radio in my Mercedes since it was lacking one completely when I purchased it. It has ISO plugs, and the headunit I purchased was also ISO, so I figured it would be plug and play, even if I might lose steering wheel controls. However, the radio only works when the power is off. If I start the car, the radio is dead (no clock), I power off the car, dead, the lights go out... and 5 seconds later the radio power up and plays. It is mind-boggling. I tried it a couple times and it did it every time. The wiring looks correct, so it really is puzzling. Any help would be appreciated, thanks.