Tucker Sno-Cat® is required to run the latest emission systems with our Cummins diesel engines. The late model 2000 groomers are outfitted with a small LED light below the master switch. This small, amber light is an indicator that the DEF or Diesel Exhaust Fluid pump is running. DEF fluid is highly corrosive and incredibly sensitive to freezing. When you are out running your club’s new groomer this year, make sure you don’t shut off the master switch before the light is out.