1998 Ford Explorer Speedometer

Ok I would test the VSS (vehicle speed sensor) first and see what it is doing. If you have a digital mulit meter and would like to test it yourself then let me know and we will go from there.

Ok first we are going to do a self test which is using the cruise to tell us weather or not there is anything wrong with the speed sensor first ok. Now this sequence will need to be kind of quick but you must pay attention to the cruise light as it will flash and give codes to tell us weather or not to do the test on the VSS ok. You will be pressing the buttons on the steering wheel for the cruise so it will talk to us ok.
1) Put in park and set E-brake, while holding the off button turn the key on engine off. The cruise light should have flashed once to tell us it in self diagnostic mode. If it didn't flash then repeat this step.
2)release the off button within 5 sec of turning on the key and now press the on button. Now press the remaining speed control button's in the following sequence ok - ON, RES, COAST, SET/ACCEL. As each button is pressed the cruise light will flash, wait till the light goes out to press the next button.
3)After completed the cruise light will flash to indicate pass or fail. Count the flashes.
4) Now the actuator will perform a test and lift the throttle 1 to 10 mm after throttle has returned the turn off key.
Get back to me after this with how many flashed you counted and we will go to the next step.

Ok you need to hold the off button then turn the key on with the engine off (meaning don't start it but put the key in the run possition) Then you should see the light flash and then follow the rest of the steps.

Ok with that it is saying that the cruise control will go into the test and the first test passes but that is it so the VSS needs to be tested now ok. First check fuse number 10 it should be a 7.5 amp fuse make sure it is good. Other wise I need you to unplug the cruise harnes and then the abs harness and do a ohm test between the servo module connector number 3 and the abs module harness connector number 10 let me know what the ohms is and this test is done with key off. Here are the pics of the harnesses so you know what term it what.
Cruise harness

The ABS harness

Ok with that test it say's the speed servo is bad. However this don't answer why the speedo don't work so lets do another test on the VSS.
Now with key off unplug the speed servo connector and hook you multi meter between term number 3 and ground and set it on ac setting and drive the car after 30 mph it should give you a voltage reading let me know what you find. If you get nothing then the VSS is no good and needs to be replaced.