Fan Solenoid Valve Gets Hot!!

Discussion in 'Freightliner Forum' started by gudethangs, Sep 27, 2016.

  1. gudethangs

    gudethangs Bobtail Member

    23
    3
    Dec 14, 2014
    0
    Everyone
    I got a 2005 FTL Century Class. Fan won't turn on when it suppose to. Replace fan solenoid valve, plugged it in and the solenoid begins to heat up!! Can't even touch it unless unplugged to cool off. Engine is off & the connector is energized when its not suppose to be. Any ideas guys why the fan solenoid connector is energized when the truck is off?? Thanks.
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. baha

    baha Road Train Member

    4,137
    2,832
    Jul 25, 2013
    ga
    0
    Some fans are run with air on to freewheel others run with air to spin, re ck. wires and ground wire?
     
  4. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

    1,778
    1,722
    Jun 14, 2009
    romulus,mi
    0
    Solenoid is 12v+ key power (has a dedicated 10 amp fuse in upper left corner of fuse box) Ground is supplied by ECM. It should not be 12v+ battery. The ECM removes ground when it commands "fan on" So in short, you should have key power and ground to solenoid for fan to be "off"
     
  5. Showtime89

    Showtime89 Light Load Member

    105
    106
    Feb 25, 2016
    0
    what if you have no power when key is on?
     
  6. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

    1,778
    1,722
    Jun 14, 2009
    romulus,mi
    0
    check the fuse that I told you about above.........
     
  7. Showtime89

    Showtime89 Light Load Member

    105
    106
    Feb 25, 2016
    0
    I checked.. I will check again
     
  8. gudethangs

    gudethangs Bobtail Member

    23
    3
    Dec 14, 2014
    0
    Thanks for all the replies. I had the mechanic check out all fuses but still can't figure out why the fan solenoid valve has power & heats up when truck is not on!!
     
  9. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

    1,778
    1,722
    Jun 14, 2009
    romulus,mi
    0
    The red 10 amp fuse labeled "engine fan" in upper left corner of fuse box should only be "hot" with key on. If it is hot with key "off" then you have a problem with PDM (fuse box)
     
  10. gudethangs

    gudethangs Bobtail Member

    23
    3
    Dec 14, 2014
    0
    Thanks for your reply. Not sure what happened but I replaced the coolant thermal sensor & solenoid valve is working normal now. Fan turns off/on as it should. Not sure if replacing sensor had to do anything with the ground or not but just relieve fan is working properly(knock on wood!!!) Thanks again for all the help...
     
    Last edited: Sep 29, 2016
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.