We have a 1996 Volkswagen Passat V-6, the automatic transmission will not go into overdrive. it shifts perfectly smooth into every gear, but will not go into OD...Any help is much appreciated.

P.S. Only has 80,000 miles on it. VW Dealership wants $200 to do a diagnostics on it...We have a used car lot and purchased this from an auction, so I do not have any history on the vehicle..