How to Install a Headlight Relay Harness in Your 2004 GMC Sierra 1500 morsunled.wordpress.com

The 2004 GMC Sierra uses a dual-headlight system with separate bulbs for low beam and high beam on each side. Some relay harness kits are designed for this configuration, while others may require minor modifications. If your kit includes only two output connectors, verify that it is designed to power both filaments of a dual-filament bulb or that you have purchased the correct kit for your application. The parking lamp circuit on these trucks is separate and is not affected by the relay installation.