Confirmed by MLB Rule 5.10.m.4
Enforcement of Mound Visit Limits. A manager or coach who crosses the foul line on his way to the mound after his team has exhausted its mound visits must make a pitching change, unless the pitcher has not pitched to a minimum of three consecutive batters in accordance with Rule 5.10(g), in which case the pitcher shall continue to pitch only to complete pitching to his first three consecutive batters (or the end of the inning, whichever comes first) in accordance with Rule 5.10(g). If a manager or coach believes an exception to the mound visit rule applies, he must confer with the umpire prior to crossing the foul line. In circumstances in which a team is forced to make an unintended pitching change by operation of this Rule, and there is no relief pitcher warming up in the bullpen, the manager or coach who violated the Rule by exceeding his team’s allotted number of mound visits shall be subject to ejection from the game. The umpire may allow the substitute pitcher additional time to prepare to enter the game.