P1477 - Medium Fan Control (MFC) Primary Circuit Failure

WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

P1477 - MEDIUM FAN CONTROL (MFC) PRIMARY CIRCUIT FAILURE

Description:	Monitors the medium fan control (MFC) primary circuit output from the PCM. The test fails if: With the MFC output commanded on (grounded), excessive current draw is detected on the MFC circuit; or, with the MFC circuit commanded off, voltage is not detected on the MFC circuit (the PCM expects to detect IGN START/RUN voltage through the medium speed FC relay coil to the MFC circuit).
Possible Causes:	Open or shorted MFC circuit. Open IGN START/RUN circuit to the medium speed FC relay. Damaged medium speed FC relay. Damaged PCM.
Diagnostic Aids:	When the MFCF PID reads YES, a fault is currently present. An open circuit or short to ground can only be detected when the PCM is not grounding the MFC circuit. A short to power can only be detected when the PCM is grounding the MFC circuit. During the KOEO and KOER self-test, the MFC circuit is cycled on and off. Using Output Test Mode on a diagnostic tool, when commanding the low speed fan on, the PCM also activates the medium speed fan output.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
Freestar/Monterey	GO to KF: Fan Control relays STEP 25	GO to KF: Fan Control relays STEP 25	GO to KF: Fan Control relays STEP 51
All Others	GO to KF: Fan Control relays STEP 6	GO to KF: Fan Control relays STEP 6	GO to KF: Fan Control relays STEP 47