Hi Jason, on my 91 Baronet I had that problem. I pulled the speedometer out and not knowing what I was doing started flipping the dip switches on the back. I ended up calling the manufacturer and they gave me the formula to reset the switches properly. Don’t do what I did, until you take a picture of the switches. I had a lot of electrical corrosion problems mostly from the age of the equipment, once the switches were moved and were put back correctly the speedometer worked great. On my Marquis the speedo went bad and I put a GPS operated speedometer in it and the company(can’t remember now but can find it if you need it) set the mileage to the correct number so all is good. Hope this helps.