A flashing light indicates normal pulsing voltageGM IAC testers (flat and square four connector applications) with red and green LEDs
Eight noid Light covers: GM PFI, Ford TBI, Geo TBI, Bosch PFI, GM TBI, GM SCPI, Bosch 2, Multec 2, plus two GM IAC testersExtension HarnessMolded plastic case
Checking electrical signal at the fuel injector