Instruments and Controls Identification 01/18/95 f600151a Fig. 2.30, Tachograph, Optional Exterior Switches Battery Disconnect Switch, Optional The switch is used whenever service operations re- quire that the batteries be disconnected. It is also used whenever the vehicle is placed out of service for extended periods, to prevent battery discharge. See Fig. 2.31 . IMPORTANT: The battery disconnect switch does not completely isolate the batteries from the electrical system. For service operations that require that the batteries be disconnected, al- ways shut down the engine and remove the negative battery cables. 01/18/95 f600150a Fig. 2.31, Battery Disconnect Switch 2.31