Theres only a single ground wire coming off the hitch wire harness. Ours is White w/ black stripe (or black w/ big white stripe, depending on how you look at it) Both lights should be grounded there. Here's a pic of how a typical 7 pole trailer hitch is wired: (note it doesn't fully match what Toyota did)




2003 4RUNNER WIRES:
(Ground) = thick white wire w/ black stripe
(right turn/stop) = Brown
(left turn/stop) = Red
(tail lights) = green w/ black stripe

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Black 2003 SR5 V6 4WD (Option Pkg C) ClearBra, painted pinstripes Mods: Rear glass limo tinted/ fronts 27%, Sunroof Deflector, Auto Dimming Mirror, VVT-i emblem, Homelink, Valor Tip -- Aftermarket: Weathertech Deflector, AVS Ventvisors & Tailshade tail light blackouts, Silver Star bulbs, 7.2" Widescreen TV/DVD, PNI Wayfinder Compass, K&N Air Filter (Part #33-2281), Husky Cargo Liner, Wood Trim Kit, Third Brake Light Flasher, Amber Whelen Slimlighter (aux. rear hazard warning) Rear foglamp housings modifed for aux. tail/brake/signals/hazard (See Rear Fog Mod Thread here : http://www.toyota-4runner.org/showth...threadid=1137)