odamiter isn't working
For the 88 Mustang, if your odometer isn't working the speedometer isn't either. You need to replace your speedometer cable. It must have broken or come loose. http://www.latemodelrestoration.com/item/LRS-17260B/79-93-Ford-Mustang-Speedometer-Cable
I had the same problem. The worm screw had worn down and I had to replace the instrument cluster. I got one at a salvage yard for about 30 bucks and replaced it myself. It is not a difficult job, but it is time consuming ( you have to be very careful not to crack any trim pieces).
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