Rear light question
 

My back up lights only work with the other lights off. In other words, headlights and or parking lights on, no backup lights. Is this a switch issue? If so, which one?

Do you have a good enough ground at tail lights?

I have enough that the brake lights, turn signals, and side markers work. But sometimes the left rear brake light goes out when in reverse.

As a general rule, if something electrical is acting goofy, look for a bad ground. Clean all connections and grounding points. Make sure all of the bulbs and sockets are clean and corrosion free.

There you go.:)

Make sure your using the correct bulb also.. Good Grounds is a must....