I was recently informed to a burned out tailight on my right, and a dim one on my left. Not one to take chances, I checked every bulb in my system (other than the brake lights - no 2nd person). My backup lights aren't coming on - but the bulbs are fine. Where is the switch/sensor located for these bulbs? (Somewhere in the linkage I assume) - haven't crawled under her yet. Knowing in advance would be easier.