Signal Waveform
WARNING: This page is about a different car, the 2014 Hyundai Veloster and 2013 Hyundai Veloster. However, it is still accessible from the selected car via links, so may be relevant.
The three waveforms below are taken from the #1 and #4 injectors. The top waveform is from the high side (feed side) of the #1 and #4 injectors, while the middle waveform is from the low side (ground side) of the #1 injector and the bottom waveform is from the low side of the #4 injector.
The middle waveform is the same as the top waveform because there is no ground for the circuit. With no current flowing in the circuit, the #1 injector is not energized and fuel does not flow.
The bottom waveform shows that ground is supplied and there is a voltage drop across the #4 injector. With current flowing in the circuit, the #4 injector is energized and fuel flows.