Hello...I'm new here and I have researched this and cant find the answer to this. I hope you can help me?
I just dropped in the Avic d3 into my 01 Mercedes SLK230 and everything is working perfectly except the darn speed sensor!!!
Yes, I checked if its receiving the signal and it is...the problem is that I believe its getting too many signals!! When I'm going 30 mph the AVIC shows 175MPH.....why??? Is there a way I can cut the pulses in half or any other way to fix it? Again, I do have the right wire because when I'm parked the value is zero...with speed it increases way up there to 175mph. I also checked the wire and the color is correct....
Please helpppppppppppppppppppppppppppppppppppppp 
Ski