Will not turn over

Hello my name is Dave.

First thing we need to check is if the anti-theft light is flashing with the key in the run position, If it is flashing then there is an issue with the security system. I would also check the voltage at the starter itself and make sure it has the same voltage as the battery, if not you would need to check all of your battery connections including the ground at the block. If the security light goes out when you turn the switch to run the next thing I would check would be the fuse which is #24, if the fuse checks to be good the next thing I would check is what Cadillac calls ignition switch mechanical block which is on the steering column which has the same function as a neutral safety switch. I have attached the diagram showing the circuits for the starter/charging systems to guide you in testing these and this link will take you to our tutorial on tasting fuses:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

When you look at the diagram you can see the wiring that needs to be tested going from the ignition switch to the starter.
here is our tutorial on testing wiring:

https://www.2carpros.com/articles/how-to-check-wiring

I would start with the signal wire at the starter and see if it is getting voltage when the switch is turned to the start position. Also a quick test is to put it in neutral and see if it starts, if it does then the ignition switch mechanical block on the steering column is faulty. If you could keep us up to date on your progress we would appreciate it and thank you for using 2CarPros!