A line lock is a device that allows the front brakes to lock independently of the rear brakes via a switchThe device is an electric solenoid that controls a valve which is placed on the front brake line, and is controlled by a switch Normally, the valve is open and allows fluid to pass through to the front brakesHowever, when the brakes are applied and the solenoid is activated, the valve closes to trap the brake fluid, keeping the front brakes applied until the switch is released.
ABS when active will receive its data by its data from the abs sensors, it is trying to control the brake fluids pressure send to the brakes, to prevent lock up, it is constant controlling and monitoring the pressure send to the brakes and by that it is not interferring by a line lock kit, the abs computer will regulate pressure only sent towards the brakes, During normal driving, the solenoid is open and the brake pressure is applied to the ABS unit exactly as it is without the solenoid installed. Only when the solenoid is powered via the dash button is the brake line valved off and pressure held on the front brakes.
Enjoy having a line lock kit on the supe, and no worries for the ABS.