The In-Line Spark Checker from S & G Tool Aid tests spark plug circuits, electronic fuel injection signals and idle air control circuits for recessed plugs, noid lights and the IAC test lights kit. This tool offers eight noid lights to check GM PFI, FORD TBI, GEO TBI, BOSCH PFI, GM TBI, GM SCPI, BOSCH 2 and GM MULTEC 2 systems.