I have a 2008 eclipse. The key was lost, so I took it to the dealer to get a new one programmed. They were able to program the key transponder, but can not program the key less entry, which also disables the alarm. They are telling me they can't program the keyless entry because I have an aftermarket car stereo. This doesn't sound correct to me.
Thank you for writing in. The aftermarket radio is likely stopping the new key fob from communicating with the security system. While it may seem strange, many automotive manufactures use the stereo's programming to help other parts of the car communicate with each other as well. There may be an issue with the way the new stereo was installed, wires left disconnected, or simply a communication error between the two systems. The dealerships are best suited to handle issues with the security system, and you may want to try using another dealership if you can find one near you. Good luck!