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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Powertrain DTC Charts & Descriptions (Except Diesel & Hybrid) >> DTC Diagnosis >> DTC P1479: - High Fan Control Primary Circuit

DTC P1479: - High Fan Control Primary Circuit

DTC P1479: - HIGH FAN CONTROL PRIMARY CIRCUIT

Description:  Monitors the High Fan Control (HFC) primary circuit output from the powertrain control module (PCM). The test fails if the HFC output commanded on (grounded), excessive current draw is detected on the HFC circuit or, with the HFC circuit commanded off, voltage is not detected on the HFC circuit (the PCM expects to detect VPWR voltage through the high speed FC relay coil to the HFC circuit).
Possible Causes: 
  • Open or short HFC circuit
  • Open VPWR circuit to the high speed FC relay
  • Damaged high speed FC relay
Diagnostic Aids:  When the HFCF PID reads YES, a concern is currently present.
An open circuit or short to ground can only be detected when the PCM is not grounding the HFC circuit.
A short to voltage can only be detected when the PCM is grounding the HFC circuit.
During the key on engine off (KOEO) and key on engine running (KOER) self-test, the HFC circuit is cycled on and off.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All GO to Pinpoint Test KF .
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