I have 1989 jeep comanche 4.0/Nv3550 with 1999 xj conversion. My tach, engine temp, battery, and oil pressure and fuel all register. Speedo does not work. I have the dash pulled apart and lubed up C1 and C2 with dialectic grease. I also order a new C2 from the dealer and just installed it. Still speedo is not working. Driving me nuts. What could be causing this? A ground? I've checked my grounds and fuses. Also checked the airbag issue i read about. I am at a lose. Please help with some friendly advice. Sick of not knowing my speed or current mileage.