Engine Fan Wont Turn Off

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Turbrospeed, Oct 26, 2021.

  1. Don379

    Don379 Heavy Load Member

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    did some digging and he owns a 97 freightliner with detroit 60
    In my my case when i had this issue, it turned out the ecm was bad but that was on cat motor.
     
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  3. Turbrospeed

    Turbrospeed Light Load Member

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    97 Freightliner Century Class with its original S60 12.7 Engine... Last six digits of vin are 884754
     
  4. Turbrospeed

    Turbrospeed Light Load Member

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    I have a good feeling that you might be right because sometimes the fan solenoid will freak out and blow off mutiple times. Also i did replace the ECM last year with a supposed good used one according to the guy who installed it. Unfortunely some ahole stole my previous ecm when i use to live in Miami. What is also weird is that even with my old ecm it did the same thing sometimes.
     
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  5. Rideandrepair

    Rideandrepair Road Train Member

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    My 99 had a problem since new, fan would come on for no reason. Any given time, didn’t stay on always, just erratic. There was a bulletin on it. Fyda Freightliner in Youngstown Ohio. Sold Me a pigtail upgrade kit. I spliced it into the harness near the solinoid. I had to push a connector out, and crimp an end on a wire. Instructions with kit. Fixed the problem, after a years of asking everyone about this bulliton I’d heard about. Don’t know if you’re 97 was affected. Worth a shot though. My 2000 is controlled by power distribution module, located in the fuse panel, along with a few other sensors that were eliminated. It sometimes acts funny. Kicks on, for no reason. Not often, but still isn’t right. This is an old problem, it’s a Freightliner specific problem, not Detroit.
     
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  6. Turbrospeed

    Turbrospeed Light Load Member

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    Yea my truck has always done that for the past 6yrs but i guess now it really messed up, I will most likely save myself the headache and just put a switch to the solenoid so i can turn the fan on/off whenever. I prefer this since my idle up doesnt work and i have to use my triangles to keep the idle atleast 700-800 rpms, if i just leave the fan turned on, it wont be cycling every couple seconds and lower the rpms. I try my best not to idle but since i tend to drive all night and sleep until the afternoon, sometimes it gets really hot in the truck. My last resort is to change that water temp sensor in which i have there to change. I been home for the past couple days and just been lazy :laughing6:
     
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  7. Turbrospeed

    Turbrospeed Light Load Member

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    Hey guys i forgot to update on what i did.

    I ended up putting a switch to control the fan manually from the ground output wire. I wasnt going to pay hundreds of dollers to a shop to fix the problem and have my truck there sitting for who knows how long. If i do turn on the ac while stopped, i just flip the switch n done.
     
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  8. MM71

    MM71 Heavy Load Member

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    It is probably either a failure your High Pressure sensor on the Air Conditioner, or a failure of the wire connecting it to the computer. Lots of times the ground fails somewhere in the harness.
     
  9. Turbrospeed

    Turbrospeed Light Load Member

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    I put the high pressure switch new and nothing...Am pretty sure its the ground from the harness to ecu but am not messing with that....The switch i put works perfect
     
  10. Rideandrepair

    Rideandrepair Road Train Member

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    Isn’t it still going to be coming on when it’s doesn’t need to ?
     
  11. Turbrospeed

    Turbrospeed Light Load Member

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    Nope it wont because I put the switch directly to send ground whenever i want.
     
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