Starter Motor Request (SMR) Circuit
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 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 START position and the transmission range sensor ignition lockout circuit allows the starter to engage.