Cadillac Repair: Car Computer, purple wire, air blow

Question
Hello, I have a 1989 Sedan Deville, and here recently, when ever I start my car, the air blow comes on high, blowing out heat, and sometimes cool air, on the controle pannel where the fule useage, and the tempature lights up, it lights up with the following to letters >>(d) and sometimes it lights up with the following letter >> (c) the radio comes on, but the light in it is jumpy. I would like to know what the problem is, and do, should I replace the computer in it..? I'm thanking you in advance for your help.

                                       Tee  

Answer
Hi BigTee, Is just the fuel data panel displaying c or d and the climate control panel ok or do both panels display letters? If fdp is displaying letters only then unplug both panels and switch them. If the fdp still displays letters then it needs to be replaced. If the ccp now shows letters then the body computor or connector could be bad or there is a short to ground or open in circuit 719 which is a purple wire from terminal V at the fdp and terminal B1 at the body computor. Let me know what the panels display after switching if you need more help. Bill