So I wire my brake light (from the spoiler) to the right tail brake light.

IT worked fine...until my friend told me that when I turn the turn signal to the right, the brake light on the spoiler blinks with it. On the contrary, when signaling to the left, I got no problems.

help! (btw, if you're gonna tell me to wire to the 3rd brake light, tell me how to reach it. thanksl!!!

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2003 E55 AMG
2007 FJ Cruiser