Cadillac Repair: 1988 Cadillac Eldorado (4.5 liter), napa auto parts, haynes repair manual

Question
QUESTION: I am having two codes coming up as current; even after I clear the codes. They are (120)-twilight delay pot ; and (121)-twilight enable switch.  My Haynes Repair Manual does not specify any repairs, or part replacements related to these codes. I would like to correct the problem(s) so that these codes will not re-occur.  Any assistance on this matter would be greatly appreciated.  Thank You

ANSWER: I have been out of town, Do you still need help ?.

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QUESTION: Yes , I am still trying to fix this particular problem.  I have been calling around to new and used auto part stores about the possibility of having to replace the Twilight Sentinel switch(head light switch).  However, if I purchase another switch, there is different kind of switches for this year El Dorado. I saw a picture of one that was sold by Napa Auto Parts. The switch was identical to the one in my car with the exception of one thing.  The Napa version had an extra control on the switch. It is a Dimming Sentinel control.  My current switch does not have that.  Would that switch still work in my car?; am I even going in the right direction to eliminate these codes(120)%26(121)?  Once again, thanks for any help that you could offer.
         Rob

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.