Tim, the box that causes the service light to come on every (?) 30k miles is
in the speedo cable underneath the van...speedo cable runs from LF wheel to
this box, then on to the odometer.  If your odometer doesn't work, the light
will still come on at regular mileage intervals.  Drop your spare tire and
follow the speedo cable from the wheel.  The box has a button on it
somewhere to reset the light.  Reset the box and your light should go out.
Fetner