Replacement trailer wiring harness for vehicles originally equipped with a factory installed tow package – perfect for replacing or upgrading a damaged or missing factory harness. Quick and easy plug-in installation – no cutting or splicing necessary; simply plug into the existing vehicle connectors, insert the provided relay and you are ready to start towing. Upgrades vehicles equipped with 4-flat factory wiring to a 7-way connector; original 4-flat connector will also remain functional after installation. For use with vehicles originally equipped with a 4 pole harness only – will not work on vehicles factory equipped with a 7 pole harness. Instructions are easy to follow and include detailed photos; backed by Tekonsha’s 1 Year Limited Warranty.