if it does come on then is it the sensor going out or is there something else causing this

 

The wire from the trans to the reverse lights is connected to the neutral safety switch and not a sensor. If you have power to the switch but nothing out either the switch is bad or there could be something wrong with the wiper on the crows foot inside the trans. The later is unlikely. Pull the switch and manually depress the actuator ball on the switch and test it for continuity to isolate the problem inside the switch. No continuity requires replacement of the switch.