have recently bought new genuine fiat oe radio cd part No 735 299 652 (ebay)to go in early 04 doblo, however it wont work when plugged in, display reads 'CAN CHECK' & will do nothing more, I think this relates to canbus system, am I correct in thinking that an early 04 doblo is not 'canbus' equipped & so this unit is not suitable?, the plugs & pins are the same as on the radio cassette but there are small differences on wiring diagram stickers, 3 pins are marked differently, cd has CAN A, CAN B, & a sun symbol, radio cassette has these 3 pins marked NC. any help appreciated.