one fan on high

Discussion in 'Dodge Charger Electrical Problems and Questions' started by Tnaslym, Jul 20, 2017.

  1. Tnaslym

    Tnaslym New Member

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    Location:
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    Vehicle:
    Daytona
    Trim?:
    Daytona
    Color?:
    Plum Crazy Purple
    About a month ago my 07 Daytona started running with one of the radiator fans running really high and the other not at all. I was getting a code saying the radiator fan relay was bad so I changed all of the relay's associated with the fans and still got the same thing. So I took out the assembly and found that the fan that wasn't spinning was seized and the connector was melted. So I replaced the assembly and the wiring connection and still got the same thing. One running high and the other doing nothing.

    So I did some research and decided to replace the FCM. I replaced with a used FCM with the same exact part #. The car cranked up fine but not even 20 seconds later with a cold engine that one fan kicked into high and the other did nothing. Any advice is welcome. Thanks in advance
     
  2. Tnaslym

    Tnaslym New Member

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    Please help me I'm begging
     
  3. djalbin

    djalbin Active Member

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    I assume the DTC was either P0480 (fan-1 control circuit) or P0481 (fan-2 control circuit). Obviously there was a problem with the one fan (seized and melted connector). The fact that the fans are not behaving correctly, after replacing the fan, connector and relays, indicates there is still a problem in the control circuit.

    The PCM decides when to turn On/Off the radiator fans. It does this by receiving input from the ECT sensor (engine coolant temp) and sending a signal to the radiator fan relay (it's a pulse width modulated signal). The FCM controls power to the fans by completing the circuit to 12 volt power (high side driver). But the FCM also stores vehicle configuration data. Since the replacement FCM didn't fix the problem ... I would consider reinstalling the original FCM.
    If you reinstall the original FCM, check the condition of the wiring, pins and connectors.

    You said you replaced all the fan relays. There's three ...
    fan high/low control
    fan high
    fan control

    There's also the fused B(+) battery 12V feed circuits. Check all the fused B(+) fuses to see if any of them are blown. The melted fan connector indicates a high current condition and this may have blown the B(+) fuse.
    Check the wiring harness between the fans, fuse box, FCM, and PCM. P0480/P0481 can be caused by a control circuit being open or shorted to ground.
    .
     
  4. Lakke

    Lakke New Member

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    Hi, Another related question, do you know at what temp the fan is supposed to start?
     
  5. djalbin

    djalbin Active Member

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    When I installed my 180°F thermostat I had to change the fan settings from the stock 203°F thermostat. The stock fan settings were listed in the DiabloSport programmer before I changed them; but I don't remember the exact settings ... they were somewhere in the range of 209°F to 212°F.
    The fan settings for the 180°F thermostat are 189°F for low speed, 192°F for medium speed and 194°F for high speed operation. So 209°F to 212°F is abut right for a 203°F thermostat.
    Maybe one of the forum members with the stock thermostat will have the exact settings.
    .
     
  6. HemiLonestar

    HemiLonestar Member Military

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    Gimme a few hours I'm going to pick up my Magnum from the shop. I had to set it back to stock, so when I go to retune I can write down the stock fan settings.
     
  7. Lakke

    Lakke New Member

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    Thanks for a quick reply. Reason I ask is my radiator leaks somewhere around the drain valve, but only when it's hot. When I stop and idle it goes up to about 206F but the fan don't start. If i disconnect the temp sens it starts and runs max.
     
  8. djalbin

    djalbin Active Member

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    When you disconnect the temp sensor the PCM can not get a reading on the temp; so it probably runs the fan on max to ensure adequate cooling.
    .
     

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