Fuse and relay box diagram BMW E90 - fusesdiagram Fuse and relay box diagram BMW 3 E90. Identifying and legend fuse box. BMW Engine Electronics Fuse Pack – In Underhood E-Box, E46 Aug 10, 2010The Engine Electronics Fuse Pack supplies power to many of the engine operating systems. The pack is located in the under-hood E-Box (Electronics Box). Some models have the E-Box on the driver’s side and some are on the passenger side.