OTC 7187 TBI Noid Lite for GM Noid Lites are a proven test device to quickly determine if the electrical signal is present at the fuel injector 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 Works on 1984 to current Ford F600 F700 and F800 series having Lucas Girling hydraulic brakes