So I got my new Thule Trailblazer hitch bike rack on today, start up the FJ, and BEEEEEEEP!!!! I'm thinking, wtf?? I turn off the parking sensor, and beep goes away. oh dear, LOL!! Guess I'm on my own in reverse when the rack is on, ha!!!
Same thing happened to me the first time I put a hitch rack on. Isn't that just the case - when it's most important to have some extra help backing up, the reason you need the help prevents you from getting it!