Ignition Circuit Sense

This circuit is used to tie the ignition switch to the PCM. When ignition switch is in RUN or START positions, battery voltage is supplied to the PCM. This is how the PCM "senses" the ignition is on. This circuit is also used to "wake up" the PCM. Voltage can be as low as 6 volts and the PCM will still function. Voltage is supplied the PCM circuit through an 8-volt regulator. This allows the PCM to perform fuel, ignition and emissions functions. The 8-volt regulator voltage also supplies power to a 5-volt regulator.