Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, p0650 code no dashlites at all.. in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; 03 cts p0650 code (mil circuit) no lights at all on the dash or shifter, but radio and ac controls ...
03 cts p0650 code (mil circuit) no lights at all on the dash or shifter, but radio and ac controls work. All started when I disconnected the TCM(with the battery disconnected) chasing down another problem..Also car wouldn't start at first afterwards, reset ECM and the car started OK. After about 12 hrs or so, the car reverts to not starting without a reset.Does the TCM have a direct connection to the dash?
Sounds a little like worst case bad ECM, there seem to be quite a few threads with the 2003 guys experiencing ECM issues.
I would check all your under seat fuses and under hood fuses also that relate to the MIL circuit and see if one might have blown.
When you clear the code does it come back?