DETECTING ELECTRIC OVER HYDRAULIC TRAILER CONNECTIVITY

A brake controller system includes a brake controller that controls the brakes of a towed vehicle based on acceleration. The brake controller sends signals to the brakes of the towed vehicle. The brake controller sends signals to determine whether the trailer brakes are properly connected. The signals may include a pulse train. The pulse train charges hydraulic braking systems for resistive testing. The brake controller determines whether the brakes are connected.