Hello can someone help me with my speedo problem i have a 1990 mustang gt 5.0 and my speedometer wasnt working at all so i replaced the cable and it works for about 10 mins the it just fails. what could be the problem thank you .

 

everything else in the system could be the problem. speedometer itself, gear at end of cable, gear in tranny.

 

Check and make sure the cable is completely seated into the transmission, and that the plastic gear isn't missing teeth or chewed up. If that is all good, I'd bet on the speedo itself.