Dodge Repair: auto trans. no shift & speedo quit same time., dodge caravan, transfer switch

Question
We parked to shop, and upon leaving, the car would not shift gears, and the speedo not working - - both at the same time.  Called one dealership, and was told it could be a 'transfer switch' or major trans overhaul. Where is this 'switch' and as an old mechanic, can I replace it myself?  We love our car, but are on a limited income.   Your service is great! Thanks! This is a 2000 Dodge Caravan.

Answer
Hello Jim
You jim cars have sire changed everything works by the compuiter even shifts the tranny . It sounds like a compuiter reset to me . I would try this first take off the pos. cable for two min and then hook it back up and see if everything is working ok. let me know in guess we have to go further pete