GM-50928-A is used to test the DEF and DPF injectors on diesel engines, as well as the fuel injectors on gasoline engines. GM-51613 DEF Injector Block-Off Plate and GM-51614 DPF Injector Test Adapters are required in turn for testing DEF and DPF injectors, while terminal test probe adapters may be necessary to test gasoline fuel injectors. GM-50928 includes GM-50928-1 DEF Injector Cable, GM-50928-2 Injector Selector Test Box, and GM-50928-5 DPF Injector Cable.