I purchased a rebuilt Chrysler PCM for my 93 Dodge Ram Diesel. It has activated everything, but speedometer is not working and therefore no overdrive, main reason for replacing PCM. From a cold start without heaters turning on check engine light comes on, and speedometer works fine. Once check engine light goes out speedometer stops and therefore not in overdrive. Any one else have this problem and know waht is wrong? Thanks

 

Pull the codes. Heres a link, post the codes back.