1987 Mercury Cougar SPEEDOMETER

MY CAR HAS THE DIGITAL SPEEDOMETER WITH THE ANALOG SIDE PANELS. ALL OF THE DIGITAL PARTS WENT OUT. I CHECKED ALL FUSES INCLUDING THE FUSEABLE LINKS. CHANGED THE DASH PANEL, CHANGED THE SENDING UNIT IN THE TRANSMISSION, THE INGNITION SWITCH AND CHASED EVERY WIRE FOR BREAKS. THE ONLY THING I DID BEFORE IT WENT OUT WAS CUT A DIODE OUT OF THE LINE GOING TO THE AIR CONDITIONER COMPRESSOR UNDER THE HOOD TO HOOK UP A DIRECT POWER FEED TO THE COMPRESSOR. THIS IS DRIVING ME CRAZY! EVERYTHING ELSE ON THE CAR WORKS GREAT. EXCEPT FOR THE CRUISE CONTROL (IT DID WORK BEFORE THE SPEEDOMETER WENT OUT). All back lights work properly on dash and I have no tach in dash to read. I did not reinstall the diode because it was only going to the air compressor.