Fig.1) Ground checking signal of APS 2 signal is for ECM to monitor APS 2. This signal drops APS 2 output voltage to below 200.39mV every 200msec. If APS 2 output voltage does not drop to below 200.39mV, ECM sets DTC as recognizing ground circuit error of APS 2 .

※ The waveform below 200.39mV is not detectable in ground checking signal waveform of APS 2 signal. Instead, the waveform which drops a little is detected. If APS 2 data of "SERVICE DATA" on the Scantool varies from 350mV to 0mV periodically, it means it works normally.