Why would a 1996 Cadillac DeVille just not start if the lights radio and dashboard go on but engine won't start-it makes a clicking noise but won't crank?

Starter solenoid is not making contact to turn starter motor. Replace starter or solenoid(which is on the starter)

!st try the battery posts. look and see if tight and clean... same thing happened to me i tightened it ,and the caddy started right up