X AUTOHAUX Dual Electric Fan Wiring Harness Kit 1999–2006 (7L5533A226T) — ECU-Controlled, 3-Relay Direct-Fit

X AUTOHAUX 7L5533A226T is a direct-fit dual electric fan wiring harness kit that enables ECU-controlled low/high speed fan operation for GM vehicles from 1999–2006.

This plug-and-play wiring harness replaces worn or missing fan relays and wiring to restore proper electric fan control managed by your vehicle's ECU. Built to match factory fitment for GM models from 1999 through 2006, the kit includes the necessary relay system and connectors to run dual fans at both low and high speeds without tapping engine power. Whether you’re troubleshooting cooling faults, upgrading a damaged harness, or restoring correct ECU control after engine work, this harness re-establishes the signal path between the ECU and the fans.

How does this harness re-enable ECU control of the cooling fans?

The kit routes the ECU output through a dedicated three-relay arrangement to operate both low and high speed fan circuits. Instead of a mechanical fan drawing constant engine power, the electric fans respond to temperature and vehicle signals via the ECU using this harness. That restores proper automated cooling behavior and reduces unnecessary load on the engine.

• Includes three-relay architecture for low and high speed switching
• Correct pinout and connectors designed for GM 1999–2006 ECU interfaces
• Direct wiring path reduces voltage drop compared with jury-rigged splices
• Preserves original control logic—fans triggered by ECU signals

Will this kit fit my GM truck or car from 1999–2006?

The harness is designed for GM vehicles that use ECU-managed fan control within the 1999–2006 model years, but compatibility depends on your OE connector and part number. Before purchasing, compare the included part number 7L5533A226T and connector shapes to your vehicle’s harness. If you’re uncertain, check the OE number, consult repair guides, or view an installation video to confirm fitment.

• Part number: 7L5533A226T—match to your OEM reference
• Intended for GM models with ECU-controlled fan systems (1999–2006)
• Verify connector types and mounting points before installation
• Helpful to review vehicle-specific wiring diagrams or videos

What comes in the package and what tools do I need to install it?

The kit ships with one dual electric fan wiring harness assembled with relays and OEM-style plugs to make connection straightforward. Basic hand tools and a secure mounting point for the relay block are usually all that’s required; some installations may need minor panel removal or zip-ties to route the harness neatly. Follow the vehicle service manual and any included instructions for safe connection to battery power and ECU connectors.

• Package includes: 1x dual electric fan wire assembly with relays
• Recommended tools: screwdrivers, pliers, socket set, electrical tape
• Mount relay block to existing brackets or secure with hardware/zip-ties
• Confirm battery is disconnected while making electrical connections

How does this harness improve reliability compared to older wiring?

Replacing degraded wiring and aged relay sockets with a new OEM-style harness restores clean electrical paths and prevents erratic fan behavior caused by corrosion or heat-damaged insulation. The fresh relays and connectors reduce voltage loss and intermittent faults, helping the ECU achieve consistent fan activation. Proper routing and secure mounting reduce vibration and chafing that often cause failures in older harnesses.

• New relays and connectors eliminate corroded contacts
• Improved wiring insulation resists heat and abrasion
• Better electrical continuity reduces false signals to the ECU
• Cleaner installation helps prevent future wear and failures

Who this is for: The X AUTOHAUX 7L5533A226T harness is aimed at DIY mechanics, professional technicians, and owners of GM vehicles from 1999–2006 who need to restore or upgrade ECU-controlled dual fan systems. It suits anyone replacing a failed fan relay assembly, repairing heat-damaged wiring, or ensuring proper low/high speed fan operation after engine or cooling-system service. Confirm your OE part number and connector style before ordering to ensure a correct match.