Circuit Operation

The volume air flow sensor power is supplied from the MFI relay (terminal No. 4), and the ground is provided on the ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T).
5 volts power is applied to the volume air flow sensor output terminal No. (terminal No. 3) from the ECM (terminal No. 90 - M/T) or PCM (terminal No. 65 - A/T). The volume air flow sensor generates a pulse signal when the output terminal and ground are opened/closed (opened/short).