My sensor buzzer is on constantly wgen i put car in reverse

check sensor for debris or wiring problem

Sounds like a faulty sensor or the sensors have got water in them.
With the handbrake on and your wheels chocked turn the key till the ignition is on but don't start the engine. Then put the car into reverse and try unplugging each sensor till you find the faulty 1. (the sensors are the round dots on your rear bumper)

Water proofing the sensor with some silicone grease (or similar) after drying it out should fix your problem.

hello Troy Royce try to connect if at the reverse light..it the same concept back to basic..

what are you modifying first need to have details

Its a fuse in the fuse box it should be labeled.
The headlights are switched by a sensor either back of the mirror or on dash.

Locate the buzzer behind left end of dash (under) it will have a green and yellow wire plugged into it, simply unplug this connection:)

because the prius is such a nightmare to work on,i would suggest you try to live with the noise or park it where you dont have to reverse.you cannot just bypass the buzzer.......

Try to clean rear parking sensors. Check also electric cables and connections, clean if necessary. Commons faults are sensors out of order. If one or more sensors faults you hear only a continous constant noise when you put in "R" gear. You need a VAS, VAG-COM, Bosch KTS, ... diagnosis scantool. The factory parking system will be scaned from errors with this instrument, and you will find exactly which sensors are out of order (for example: rear left center sensor, rear right side sensor break off, short to ground or short to plus).

that what the back up buzzer is suposta do....when you are backing up <going in reverse> the buzzer will be active, while driving it forward it should inactive.... hope this help you out...