TM 9-2320-209-20-3-1 7-68. AIR STOPLIGHT SWITCH REMOVAL AND REPLACEMENT (TRUCKS M275A1 AND M275A2). TOOLS: 2 1/4-inch open end wrench Pipe wrench Vise SUPPLIES: None PERSONNEL: One EQUIPMENT CONDITION : Truck parked, engine off, handbrake set. a. Preliminary Procedures. (1) Vent air system pressure. Refer to Part 2, para 13-20. (2) Disconnect battery ground cable. Refer to para 7-58. CAUTION Make sure that main light switch is set to OFF position or electrical damage may result. 7-263