2004 Cadillac DeVille Q&A
2004 Cadillac DeVille Question: transmission shifting rough
The powertrain control module may have detected a fault and as a result has commanded full line pressure causing the hard shifting. The first step would be to check for stored fault code(s) in the powertrain control module. Any stored codes should be diagnosed and repaired and then the transmission operation rechecked. If you need someone to access and diagnose any stored fault codes, please use the following link to find a shop near you - http://repairpal.com/directory?address=24211&car_brand_names=Cadillac. - Oakman
The powertrain control module (PCM) can fail causing stalling, and various engine and transmission drivability concerns.