Tow Ready Trailer Wiring Harness Installation - 2017 May 25, 2018How to Install the Tow Ready Trailer Wiring Harness on a 2017 Toyota Rav4. Speaker 1: Today in this 2017 Toyota Rav4 we'll be having a look at and showing you how to install the Tekonsha T1 vehicle wiring harness with a four-pole flat trailer connector, part number 118578's what the wiring looks like installed.4.8/5(247)Category: Custom Fit Vehicle WiringBrand: Tekonsha 2017 Toyota RAV4 Hitch Wiring | Harnesses, Adapters Toyota RAV4 2017, T-One Connector with Upgraded Circuit Protected ModuLite® HD Module by Tekonsha®. One-year warranty. 3 Wire System. Wire up your tow vehicle and trailer with whatever it takes to get your trailer lights on, the..