For checking the electronic control module signal that provides direction to the idle air control motor on GM vehicles with throttle body or port fuel injection systems. Set includes: OTC-3052S signal test light for 1982 and newer GM TBI and PFI fuel injection systems with square 4-pin connector; OTC-3053S Signal test light for 1987 and newer GM Model 700 TBI and PFI fuel injection systems with flat 4-pin connector.