Rear Window Wiper Washer problems of the 1999 Lincoln Navigator

The windshield wipers come on and off intermittently without being switched on/off. They seem to have a mind of their own. The rear wiper does not come on at all most times, even when turned on. Also, the odometer lcd readout comes on and off intermittently. Several light on the dash controls panels come on and off at will as well. It just seems that there is several problems with the wiring systems or possibly in the computer. However, since it only does it intermittantly you cannot plan to check it with the dealer, because there is no telling when it will occur and how long it will last.