OTC Fiber Optic Noid Lite Extension Noid Lites are a proven test device to quickly determine if the electrical signal is present at the fuel injector. It is the simplest method for eliminating the EFI system or idle air control as possible faults on no-start vehicles. Disconnect the fuel injectors plug in a Noid Lite and crank the engine. A flashing Noid light indicates normal pulsing voltage.