hi to all. im new to this forum but not new for car repair :-) i have a problem whit my vcds. i buy it about 5 y ago from ross tech. i have no comunication whit engine all time when i have in my garage audi a6 c4 2.5tdi 95-96y (2x2 adaptor.) if i change my scaner (launch or 409 vag com) i have no problem to comunicate whit engine.... please tell me which chip is responsible for old comunication protocol in pcb?