Cadillac Repair: 1989 Seville STS - Key wont unlock door, seville sts, volt ohm meter

Question
I have a manual exterior lock on my 1989 STS. The key will turn to the left, but when turned to the right it will not unlock the door. It goes into the lock without any problem and can be easily removed.  It unlocks the trunk without any issues. Any help is appreciated.

Answer
If you are mechanicaly inclined or know of someone who is, You will need a DIGITAL VOLT/OHM METER, Simple electrical schematics, Test procedures and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture. I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information necessary to fix your vehicle.