Anti theft system is on and the car will start with q jump but won't go in gear and the ignition won't turn off all the way. I got a new battery and its still doing the same thing. Its a 2006 Cadillac cts

SOURCE: 1994 cadillace anti theft system

I just had this same problem with a '96 . do you have a vats key in your '94? you need to bypass the VATS system. read some of the blogs on this site and it will tell you how to do it. I fixed mine with a $2 resistor from radio shack.

SOURCE: 1997 cadillac deville anti theft

This might work for most:

Theft Module Re-learn Procedure without a T5O or T6O
During this procedure, the vehicle battery must maintain a minimum of 10.5 volts. If the battery is not fully charged or is weak, a battery charger may be connected.
NOTE The battery charger must NOT be set in 12 volt boost. This will prevent this procedure from working.
1. Cycle the ignition switch to the "Run" position.
2. Wait a minimum of 10 minutes, cycle the ignition switch to the "Off" position.
3. Cycle the ignition switch to the "Run" position.
4. Wait a minimum of 10 minutes, cycle the ignition switch to the "Off" position.
5. Cycle the ignition switch to the "Run" position.
6. Wait a minimum of 10 minutes, cycle the ignition switch to the "Off" position.
7. Verify the repair.

and if not try this:

STARTING DISABLED/DUE TO THEFT SYSTEM/REMOVE IGNITION KEY"
If the Powertrain Control Module (PCM) does not receive the Fuel Enable message it will use the class 2 serial data line (CKT 1807) to tell the Instrument Panel Cluster (IPC) to display the "STARTING DISABLED/DUE TO THEFT SYSTEM/REMOVE IGNITION KEY" message on the Driver Information Center (DIC) . This will inform the driver of why the engine is not starting. When the ignition is turned "OFF", the IPC will start a timer and display messages to inform the driver to wait for the PASS-Key II timer to run out. The messages will read "WAIT 3 MINUTES", "WAIT 2 MINUTES" (after 1 minutes has passed), "WAIT 1 MINUTE", and "START CAR".
If the timer was not run out, the IPC will not send the Fuel Enable message. When the PCM does not receive the Fuel Enable message, it will command the IPC to re-start the message process.
This message is most likely caused by an improper key resistor value or the IPC did not properly sense the ignition key resistance.
good luck!

SOURCE: theft system locked

To get the key out; look under the steering wheel for a plastic flat head screw. untwist it and then push the spring in and your key will be free. Then, go to your fuse box and remove the main fuses and you will hear the doors unlock when the system reset itself. Plug them back in and start your car. This just happened to me... seems the only things that were working were the navigation screen, headlights, fog lights, and reading light on the inside. Dash board was all dark except the engine light.