The turbo light should only come on at around 2500 rpm. If its on all the time check the wiring first..ensure continuity by using a meter.How old is your trak I suggest you dont attempt a repair yourself on the turbo charger unless you really know what your doing..its easy to damage it.There are a number of things that could be wrongfaulty wiring ...faulty injectors...problems with inlet and outlet exhaust ports etc.You could always get it checked out at a dealer or take it to a specialst ..I know its money but if you want the turbo functioning properly..you may want to consider this.