Vehicle Power (VPWR)
WARNING: This page is about a different car, the 2020 Ford F-550 Super Duty, 2020 Ford F-450 Super Duty, 2020 Ford F-350 Super Duty, 2020 Ford F-250 Super Duty, and 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
The VPWR is the primary source of PCM power. The VPWR is switched through the PCM power relay and is controlled by the PCM. With the ignition in the START or RUN position, voltage is supplied to the PCM through the ISP-R circuit. When the PCM senses that the ignition is in the START or RUN position, the PCM grounds the PCMRC circuit to energize the relay and close the internal contacts. With the relay contacts closed, VPWR is supplied to the PCM.