Cadillac Repair: ECM Codes/Door Locks/Belt Replacement, car door locks, frank hayden

Question
I just bought a 90 Seville (base).  Car has 169400 miles and runs great, however, I have cleared all the ecm codes and reprogrammed the computer per the manual because I had to replace the neg battery terminal connector.  VIN is:  1G6KS5331LU809058.

I still get the following codes:

E041 History
E091 History
B120 Current
B127 Current
R026 Current
R034 History
R061 History

Plus, NONE of my car door locks work either with the switch inside or even using the key from the outside.  I get no noise just nothing.  Cannot lock the vehicle.  Replace all door lock actuators?  Also, the Serpetine Belt, can I replace it myself?  How so?

Any help on how to fix any of these issues is really appreciated.  I live in a very rural setting and this vehicle is my only trans at the moment.  

Thanks

Frank Hayden

Answer
Just HOW did you CLEAR the ECM codes ?.

Did the door locks work BEFORE you replaced the battery terminal ?.

Does your door locks lock when you start the car and put in in any forward gear ?.

Do the door locks lock when you put the car in PARK with the engine running?

Yes, With pictures you can replace the belt by yourself.