9 out of 10 times it is going to be a defective voltage regulator in the alternator. If you hav gone over the vehicle and have not found a draw, your going to want to check that voltage regulator.
Cadillac stopped making the Coupe DeVille after 1993.
Cadillac Coupe DeVille
where is the horns for 1978 cadillac
The starter solenoid on a 1986 Cadillac Coupe Deville is located under the front of the vehicle. It is to the left of the oil pan.
In my 83 cadillac sedan deville it up by the break petal next to the firewall.
I believe it was 1976