Detection Condition

• DTC P1474 indicates excessive current draw detected on Low Fan Control (LFC) circuit when PCM grounds the circuit or with LFC circuit not grounded by PCM, voltage is not detected on LFC circuit (PCM expects to detect VPWR voltage coming through LFC relay coil to LFC circuit).
• DTC P1477 indicates excessive current draw detected on Medium Fan Control (MFC) circuit when PCM grounds the circuit or with MFC circuit not grounded by PCM, voltage is not detected on MFC circuit (PCM expects to detect VPWR voltage coming through MFC relay coil to MFC circuit).
• DTC P1479 indicates excessive current draw detected on High Fan Control (HFC) circuit when PCM grounds the circuit or with HFC circuit not grounded by PCM, voltage is not detected on HFC circuit (PCM expects to detect VPWR voltage coming through HFC relay coil to HFC circuit).

PCM monitors certain parameters such as engine coolant temperature, vehicle speed, A/C on/off status, and A/C pressure to determine engine cooling fan needs. PCM controls fan operation through Low Fan Control (LFC), Medium Fan Control (MFC) and High Fan Control (HFC) outputs.