Do you mean "switched from vacuum to electric"? I thought the latest fad was hydrauli
Hydraulic trailer brakes are what most people are switching from to have electric brakes. when you apply your brakes the brake controler sends a signal to the hydraulic pump motor which was located front center of trailer, then starts to run to build hydraulic pressure to apply your trailer brakes, which then you could adjust amount of brake application at your brake controller, there was never vacuum on this modle..
1977 31' landyacht Sovereign