This harness works with '05+ Silverado, OEM style e-fan assemblies for 2007 and newer (2008 frontend) trucks/suv.
Typically, this harness is used on the HD Trucks and SUV.
Note: The HD trucks are equipped with a mechanical clutch fan because it pulls more air during heavy towing. If your truck is used for daily driving and light towing then e-fans should maintain the engine temperature.
ECM activation is required for correct functionality.