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Fan override relay

Discussion in 'Peterbilt Forum' started by Cajuncowboy654, Oct 5, 2020.

  1. Oct 5, 2020 #1
    Cajuncowboy654

    Cajuncowboy654 Light Load Member

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    where would the fan override relay be in a 05 379?

    My fan won't always stay on with the override switch on. Tested the switch today and it seems fine so thinking tge relay may be going bad.

    The only relay in the fuse box i see in the diagram is called FAN LOW. Is that it?
     
    Cajuncowboy654, Oct 5, 2020
    Cajuncowboy654, Oct 5, 2020
    #1
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  3. Oct 5, 2020 #2
    pushbroom

    pushbroom Road Train Member

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    Probably isnt one. Fan override switch will go right to the ecm to tell it to turn the fan on.
    Engine type?
    Washers on the dash or turn stalk?
     
    pushbroom, Oct 5, 2020
    pushbroom, Oct 5, 2020
    #2
    spsauerland Thanks this.
  4. Oct 5, 2020 #3
    Cajuncowboy654

    Cajuncowboy654 Light Load Member

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    Sorry its a cat bxs. Washer on the dash.

    I was yhunking relay because I can hea rather relay click, sometimes it will click on and off repeatedly.

    Other times if I flip the switch multiple times it will kick on, or if I push up on the switch it will catch. Thats why my original thought was the switch. But I couldn't get the switch to malfunction when I tested it today
     
    Cajuncowboy654, Oct 5, 2020
    Cajuncowboy654, Oct 5, 2020
    #3
  5. Oct 6, 2020 #4
    Roberts450

    Roberts450 Road Train Member

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    You might be hearing the air solenoid clicking which should be on the upper firewall close to the wiper motor area.
     
    Roberts450, Oct 6, 2020
    Roberts450, Oct 6, 2020
    #4
  7. Oct 6, 2020 #5
    Cajuncowboy654

    Cajuncowboy654 Light Load Member

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    Ok so any way to fix the unreliable over ride switch issue?
     
    Cajuncowboy654, Oct 6, 2020
    Cajuncowboy654, Oct 6, 2020
    #5
  8. Oct 6, 2020 #6
    pushbroom

    pushbroom Road Train Member

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    It is most likely wiring from the switch to the ecm or intermittently faulty switch.
     
    pushbroom, Oct 6, 2020
    pushbroom, Oct 6, 2020
    #6
    spsauerland Thanks this.
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