Details You can use this harness to pin your electric fan upgrade directly through the ECU and let it control the fans (ECU does need flashed). The harness is setup to control your dual fan combo and comes wired with 05+ GM truck plugs.With this harness, you don’t have to worry about triggering your fans or using those horrible probe thermostats that never work properly. This is a must when upgrading your truck to electric fans.Fit For For 1999 2000 2001 2002 2003 2004 2005 2006 ECU Control Part Number: 7L5533A226TPackage Included:1* Electric Fan Wiring HarnessProfessional Installation is Highly Recommended.