Had baris check my tuner as the screen went blank said tuner is ok refitted it still screen blank did the test by removing sat nav and putting blue plug in it from tuner screen perfect decided to do away with tuner and extend wires on plug to allow it to go back in cradle did all the coloured wires perfectly and I assumed all the back wires were earth so I joined them all together it will not work now any ideas have all the back wires got to be joint singly