Train undershoot due to intermitent brake fault. TC ATPM to headwall, shut down cab and fault self c leared. ~~~~~ 3618 undershoot due to intermitent brake fault. TC ATPM to headwall, shut down cab and fault self cleared.  3618 ER D/L & found FC 312/314/330/331. Replaced ACU & function test - OK. Brake pressure test - OK. 3618 ACU S/N : OLD : 1447/022 NEW : 1517/052  Alan/Alcus 43901