Circuit Description

PCM contains Output Driver Modules (ODM) that provides 4 switchable ground outputs for operating solenoids, relays, indicator lights, and other devices. Each of these ground outputs has fault lines that feed back to the PCM's microprocessor. When the output is off, the output driver should receive the 12 volts fed to the solenoid, relay, etc. When the output is on, it should receive zero volts, since it is grounding the output. when PCM sees zero volts when the output is off or 12 volts when the output is on, it sets a fault line low.

DTC P1645 is used to monitor the fault line of the cooling fan control relay output and the starter inhibit output.