Electric Dual Fan Upgrade Wiring Harness ECU Replaces 7L5533A226T (Out of Stock) 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. Note: Based on 2000-2004 GM truck computers without cooling fans.