It is absolutely the TPMS light. ALL SRT-6 Crossfires came with this system. If the sensors were not in the wheels, that light would be on all the time. Look at your wheels. Do they aluminum/metal valve stems? If so, you have TPMS. Non TPMS Cars have the traditional rubber valve stems. I'm not sue why you think you don't have it, becuase you do. This light illuminates when any one of your tires loses 10% of it's air pressure which on an SRT-6 is about 3.5PSI. Check all you tires with a good quality tire gauge and correct the pressure in them to the PSI listed on the door Jam label. I believe it is 36PSI for the SRT. Once you have done this, the TPMS light will go out in no more than 5 minutes. If it does not go out, there is a fault in the system somewhere.