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john deere 644k

Discussion in 'Tractor/Loader/Backhoes' started by jeradcdn, Dec 5, 2018.

  1. jeradcdn

    jeradcdn Member

    Mar 5, 2018
    Alberta, Canada
    electrical issue somewhere , when unit is not running ( key activated) all headlamps on, front wiper works as required.
    when unit is running with all lights on front wiper will not work,but when lights are deactivated wiper works as required.
    tried grounding wiper motor to frame, no change, replaced control button panel, no change.
    there are no present codes..

    any thoughts as to where i should look next, thanks
  2. mg2361

    mg2361 Well-Known Member

    Jul 5, 2016
    Equipment Technician
    Unplug your lights one at a time to see if your wiper comes back on. Whichever light you unplug that enables your wiper to work replace that light assembly, not the bulb. One of the lights is drawing too much current which shuts down the valve power within the Vehicle Control Unit which shuts the wiper off.
    Vetech63 likes this.
  3. heymccall

    heymccall Senior Member

    Feb 20, 2007
    Monroeville, Pa
    Have 544k. Same issue. DTAC case says same thing. If yours is like mine, roof work lights on, wiper doesnt work, except if washer if activated. Replaced 3 corroded lamp assemblies. No joy.

    Tomorrow, I'll be replacing at least two with LED work lamps. Will return with answer later.