1996 Cadillac Deville Starting problems

Is this a Northstar powertrain, or a 4.9L? They are completely different ignition systems. If you had a vats problem, I don't believe you would be able to crank.

If you are not getting the theft message, the vehicle cranks, and has no spark, I would suggest you have either a faulty ignition coil, a faulty cap/rotor grounding the spark to the distributor shaft, or a faulty ignition module. What kind of maintenance has been done as far as tune up.

Like I said previously, if it cranks, and has no spark it is not a theft fault. Just for grins make sure you have approx 40 psi fuel pressure, then look toward the secondary ignition. A coil, faulty cap/rotor, ignition module, can be most of the possiblities. Assuming it has no spark on any cylinder(check more that one). I am not certain if you can have the components such as coil, or module, tested at a parts house. That may narrow it down. If you pull the cap and inspect it, the contact, and the rotor, also briefly crank it and verify at that point the distributor rotates. Sometimes the roll pin for the gear can shear.