I HAVE SWAPPED A 91 TT TRANS INTO MY 91 NA. EVERYTHING MECHANICAL WORKS BUT MY SPEEDOMETER SEEMS TO BE INACCURATELY WORKING BY 10~ MPH HIGHER.. I HOOKED UP MY TECHTOM ONTO THE PORT AND IT READS ALL PARAMETERS BUT SHOWS 0 MPH GOING DOWN THE ROAD! MAYBE MY SPPED SENSOR ON THE TRANS IS DIFFERENT... NOT SURE WHERE TO START. ANY IDEAS???