My Aerostar is have problems with the speedometer. As I reach highway speed the speedometer fluctuates wildly from 0-100 mph. then drops to zero & stays there.
My mechanic has replaced the speed sensor and it still doesn’t work. Help
The mechanic is mistaken or dishonest. The speed sensor can only be monitored by the computer that runs the car. The only thing you can monitor (By watching the speedometer) is the cable driven speedometer. It is unlikely that the speedometer or gear assembly at the transmission has gone bad. More then often it is simply the speedometer cable. The Aerostar is probably difficult to replace because of the routing of the cable. Aerostar is Ford’s problem child because it was planned in haste to compete with GM mimi vans. I have a '93 Explorer that has gone through two cables in 250,000 miles. They probably use the same cables.