reverse lights come on intermittently

I think that would be about the last thing on my list of suspects. The Prius "shift control actuator" has exactly one job: it moves in and out the slug of metal that keeps the transmission from turning when you're in Park. It's not involved with the reverse lights.

The reverse lights get power from the integration relay. Both the control input and the power output to the lights are in connector 1G on the bottom of it. The control input from the power management control ECU comes on pin 13, and the power to the lights comes out on pin 3.



The next question would be whether the integration relay is getting an intermittent input signal on pin 13 and just doing what it's told, or the input signal is steady and the integration relay itself is flaking out.

I might see if I could backprobe my meter into pin 13 and watch what it's doing while the backup lights do their intermittent thing.