[RNRea]

You probably fried the DRAC module. The speed sensor from the back of the transmission send a signal that is proportional to the vehicle speed (is is often called the VSS for Vehicle Speed Sensor). This signal goes to the DRAC module which converts this signal to one that drives the speedometer (it also feeds the computer and ABS modules). If the van no longer shifts then it is likely to be this module. If the van does shift normally then it would appear that the speedometer went bad, but my odds are on the DRAC module. If you have an email address I can send you an article (pdf format) that describes how the DRAC module works and how to diagnose it. If you are handy with basic electronics you can get another module from the junk yard and replace your old one. Let me know if you would like the article.