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Detroit Fan Clutch on all the time

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Smellfunny, Apr 2, 2012.

  1. Apr 2, 2012 #1
    Smellfunny

    Smellfunny Road Train Member

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    Jan 28, 2012
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    1995 Freightliner FLD120 Detroit with Kysor Fan Clutch.

    The fan is always running. I have no codes. I have tried the Hi-Pressure switch. I have 12 volts at the fan solenoid when I use a ground other than the ground at the connector. Using Nexiq and activating ground or deactivating does nothing. On the vehicle harness at ECM at A2 I seem to get a partial ground. Coming off of A2 and going to the fan solenoid hot side I only get 6.9 volts. I can move to a vehicle ground and it goes to 12V Any thoughts?
     
    Smellfunny, Apr 2, 2012
    Smellfunny, Apr 2, 2012
    #1
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  3. Apr 2, 2012 #2
    bender

    bender Road Train Member

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    Faulty connection or driver in ECM.
     
    bender, Apr 2, 2012
    bender, Apr 2, 2012
    #2
  4. Apr 2, 2012 #3
    freightlinerman

    freightlinerman Road Train Member

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    Make sure you get it fixed. The last thing you want is the fan to seize and go through your radiator. My dad had a similar issue with a 2005 Century with a Series 60. The fan would always be on, they replace the clutch and same issue, happened twice in a row. The third time, the fan finally seized and went through the radiator causing a huge tow bill, down time, pay for motel and freight bill. They replaced the entire hub after that and no problems.
     
    freightlinerman, Apr 2, 2012
    freightlinerman, Apr 2, 2012
    #3
  5. Apr 2, 2012 #4
    Gear head

    Gear head Medium Load Member

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    Have you tryed using a regulated air source to fan hub to see if fan releases.Does fan solnoid work if you supply 12v.
     
    Gear head, Apr 2, 2012
    Gear head, Apr 2, 2012
    #4
  7. Apr 2, 2012 #5
    Smellfunny

    Smellfunny Road Train Member

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    Yeah the fan hub works fine. My dad hard wired in a temperature controlled solenoid that supplied a ground when the engine got hot enough that got the guy through the winter time and that worked well. Now that it is hot he needs the fan for when the A/C head pressure gets high and that isn't working.
    I was figuring it was the ECM but was trying to eliminate anything I may have missed. I will try a test ECM in the morning. Was trying to save the company from buying an ECM.

    Thanks for the replies.
     
    Smellfunny, Apr 2, 2012
    Smellfunny, Apr 2, 2012
    #5
  8. Apr 3, 2012 #6
    Heavyd

    Heavyd Road Train Member

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    The ECM only provides a ground for the fan circuit, not power. Power should come from a fuse or breaker somewhere. If you have an open circuit or no power, the fan will be on all the time. The fan override and a/c are usually different inputs to the ecm. If the ECM is seeing something that would demand the fan to be on there would be a second or two when the engine first fires up that the fan would actually be off, then turn on and stay on. If the fan just stays on then there is something wrong with fan solenoid circuit. You said you put power and ground to the solenoid and all is good, and you have power there, problem is likely on the ground side. If you ground the correct pin of the OEM connector at the ECM and fan does not work, check for an open circuit. If the fan does work, check the actual terminal inside the connector body and make sure it isn't all spread apart because it won't make proper contact with the pin inside the ECM. Lastly, try a test ECM. The pin mapping is OEM specific, so make sure know what outputs are what!
     
    Heavyd, Apr 3, 2012
    Heavyd, Apr 3, 2012
    #6
    mojo2010 Thanks this.
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