Starter Motor Request (SMR) Circuit
WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2006 Mercury Mountaineer, 2006 Mercury Monterey, 2006 Mercury Montego, 2006 Mercury Milan, and 2006 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
The SMR circuit provides the PCM with a signal from the ignition switch to the PCM. The input is pulled high when the key is in the START position and the transmission range sensor ignition lockout circuit allows the starter to engage.