I have a 2004 Coupe. I recently had to replace my ignition switch. I had no problems putting it on everything fit perfectly BUT when I tried turning it on my car wouldn't start. It turns on but when I crank it on it won't start. Any suggestions on what I should do next? Please Help.

 

Any codes present? Could be the immobilizer. (NATS) Is the red security light illuminated on the dash?

We can completely bypass NATS with an Uprev reflash if that turns out to be your problem. Shoot me a PM

 

So you're using a different KEY yes? There is a RFID transponder in your key that is read by the BCM when you are cranking the ignition you need to use the key that the car was programmed to be using. You can dig the chip out of your old key and put it into the new one. Here's a few pictures of my key, I had to do the same thing. Helps if you use some flush cut pliers and cut away the side of the key just slightly so you can access the groove in the side of the RFID chip holder like I did, it's still held in with detents, then you use a small flat blade screwdriver in that groove to wiggle the holder up out of the key.

Or you can get an Uprev tune from Seymore4 which can also turn the immobilizer off in addition to making the car so much more fun to drive.

Or you can pay the dealership or a local locksmith to program your BCM to accept the new key.

You can tell if it's a NATS/IVIS issue because the indicator LED light on the left side of the dash will be SOLID RED while cranking.

 

Totally slipped my mind that he'd be using a different key. So yes, it's NATS locking you out.