CRUX SOCGM-17CRUX (SOCGM 17) GM CLASS II HEAD UNIT REPLACEMENT INTERFACE WITH CHIME, BLACK The CRUX SOCGM 17 retains factory featured safety and warning chimes in General Motors Class II vehicles. For installation of after market radios. FEATURES: Retains factory features in select GM Class II Data Bus vehicles while functioning with an aftermarket radio. Retains chime functions such as: seat belt, check engine, key in ignition, low fuel, low oil and lights on.