Question: how can motion extinguish the back-up lights?
Symptom:
1. engine off (ignition on), gear in reverse - lights work
2. engine on, gear in reverse - lights work
3. begin to back up, within 10 feet (2 or 3 seconds) lights go out

I've gone through these variations many times and it does this every
time.  Since everything works while my head is in the engine bay, what
can I check?

Thanks,
GeneP