It does not have an aftermarket alarm. I bought the vehicle used and I don't have any keyless remotes to indicate that the factory alarm was installed. In doing some research it seems that the VTSS may have been enabled in a replacement PCM that I put in last year. It was supposed to have been flashed to match the VIN number. The VIN number for the vehicle is 1B4HS28Z2XF670228 . I never had a problem until I had to replace the starter and had the battery disconnected for several hours. The current symptoms include: after resetting the PCM and reconnecting the battery, the lights, door locks, etc. will function fine until the key is turned to the "ON" position. After a few seconds in the "ON" position or an attempt to start the vehicle, everything goes dead. No lights, door locks, power windows, etc. and I get a clicking noise from the glovebox area when the doors are opened.
Let me know if there is anything else I can tell you.