TM 9-2320-209-10-1 c. Shop Van and Instrument Repair Shop Trucks Controls and Indicators - Cont. 1. DOME LIGHT SWITCHES 24 VOLTS — 2. DOME LIGHTS SWITCHES 24 VOLTS ON-OFF switch. Controls the NORMAL-BLACKOUT switch. Lets 24-volt dome light system. you control dome lights in normal or blackout condition. 4-16