This kit is an inexpensive means to warn the vehicle operator of low fuel pressure to the VP44 injection pump in the 1998.5-2002 Dodge pickup or the Freightliner FL series truck with the 5.9L Cummins engine. The warning light illuminates when fuel pressure drops below 5 psi. Low fuel pressure can be caused by a plugged fuel filter, a faulty fuel supply pump, or if a performance module has been installed increasing horsepower to over 400 HP creating a situation where the supply pump is unable to meet the demands of the injection pump. Feel free to call our parts department at 800-891-8038 with any questions.