Hello first of all, wanted to install a bass box in my sister’s corsa today! As far as so good all cables were still available from the previous owner, so everything was connected FACHGErecht and ignition. It ran until I wanted to increase the level further and then the Diagnostic light turned on and no matter what I did did not. So with the phase tester everything was under scrutiny and Batteriesplus was there; Radioplus was there and Body Minus too. Then I had to attach that to the power amplifier on each plug (+/-) was only minus on it… I am finished with my Latin….. Verm. All fuses renewed Hope you can help me