Cadillac Repair: 1995 Cadillac Sedan Deville, cadillac sedan deville, gear indicator

Question
I have a 1995 Cadillac Sedan Deville (not Northstar). I just had a front motor mount repaired and now the "Gear Indicator Fault-Service Car Soon" lights up when starting the car and also in park and neutral.  This never happened before the repair.  Did the mechanic do something to cause this?  He says it has nothing to do with what he did.  Can you help me figure this out?
Thanks!

Answer
On the transmission where the cable attaches there is an electrical gear indicator switch that may have a loose electrical wire connection or is internally faualty. If you would like pictures as this website does not allow pictures, E-mail onlineautohelp@msn.com