TM 9-2320-361-10 2-5. BODY EQUIPMENT CONTROLS AND INDICATORS (Contd) e. Shop Van and Instrument Repair Shop Trucks (M109A3 and M185A3). Key Item and Function 1 2 3 4 5 Access Ladder Sockets are used to secure ladder in stored position. Blackout Panels provide a means of covering windows during blackout. Access Ladder provides easy access to van body interior. Dome Light On-Off Switch controls the 24-volt dome light system. Dome Lights Normal — Blackout Switch controls dome lights in normal or blackout conditions. 2-16