Brian P, There are a number of things that can cause the problem with your car.

1.Do your interior lights in the center of your car up near the mirror turn on when you open the door? They are on the same circuit as other devices that open/lock your doors. If the lights are not working your fuse 9 has probable blown and needs replacement.

2.If your siren doesn't sound when you push the panic button on the FOB you need to disconnect the siren It is located under the cowl at the base of the windshield.

3.In the rear of the car the air pump that activates to lock/unlock the doors and trunk is located on the right side below the carpet and the styrofoam. It often gets soaked in water and the corrosion prevents the locks from functioning.

So you see there are a number of things that could be wrong. Number 1 is easy to determine so do that first. If you have no joy there proceed to number 2 as a failed siren can present several problems and it needs to be replaced or left disconnected. You can drive the car just fine without the siren. I have been doing it for over a decade. NO PROBLEMS. number 3 is the biggest problem. If you scan the car you may get a diagnostic code that will head you in the right direction, but the scanner needs to be able to get into the factory codes. OBD II codes won't get you where you need to go. You can determine if there is water in the rear of the car by running a piece of paper down past the styrofoam or under the car there is a rubber plug that you can slice with a knife. That won't tell you if there is corrosion on the wires, but if there is water in that space you found your problem for sure. Good Luck