1988 Cadillac EL Dorado Gear select problem

Thanks gstacey for your reply.
On both cars on the instrument panel the prndl shows all have a box around the letters at the same time.
IE: same outline around all at same time as there is suppose to be when it is in a specific gear.

The one car starts, runs, shifts OK even though it has this problem.
The second car now will not start, for awhile it would start in Nuetral buy not in Park.
It also reads slightly different on the info panel.
It says "Gear Select Problem 27"
The first one just says "Gear Select Problem"
Thanks

Thanks for the reply.
The 1st Eldorado will still start while in Park.
The 2nd Eldorado will no longer start in any gear or even when the shifter is moved around while trying to start it.
Question on either is How can I correct this?
Thanks