Towing boat trailer with surge brake. Need access to reverse light wire from 2020 Lexus RX 450h. When backing trailer, power from reverse light will energize surge brake master cylinder solenoid that allows brake fluid to return to master cylinder rather than pressurizing line and applying trailer brakes.
Does anyone know if there is access to this wire under vehicle near rear? Thanks, imperfect.

 

I’m not positive, but the SC 430 BU lights at accessible at their socket and in the cargo area. Yours may also be accessible within the light fixture.

 

For awareness, just make sure your 450H is designed to pull a trailer [mine is not].

The reverse is strictly driven by electrical motor [not by ICE].

How about tapping from reverse light(s) at the tail?

Salim