I drive a 2020 579 Peterbilt and ever time I touch the foot brake or hand brake the lights come on and stay on which causes the engine to build no boost. The shop has replaced the light switch and brake pedal valve and problem still there. They are planning on changing the TC valve tomorrow. Can someone please help? The brakes have zero pressure on the gauge when this problem occurs so I am leaning electrical. If anyone else has had this problem what fixed it?