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744h crank no start

Discussion in 'Wheel Loaders' started by rmllarue91, Jun 19, 2022.

  1. rmllarue91

    rmllarue91 Senior Member

    Joined:
    Apr 16, 2014
    Messages:
    687
    Occupation:
    field technician
    Location:
    northeast pa
    Hey hef i got a 744h was running good washed it few hours later moved it to fuel and now crank no start. No rpm on dash when cranking. i didn't have book. But pull ecm connector traced cam and crank sensor wires and ohmed them right at ecm both measure 3.1k ohms powers and grounds show 19.5 volts why cranking I'm going to download a book and get back to machine later in week but I'm not familiar with these so just looking for some insight. Thanks hef
     
  2. Bigbert

    Bigbert Well-Known Member

    Joined:
    Jan 2, 2016
    Messages:
    247
    Occupation:
    Consulting Engineer
    Location:
    Germany
    Hi member,

    possibly a silly question:
    Gear switch is in Neutral?
    T/m display showing N or NN (not neutral)?
     
  3. rmllarue91

    rmllarue91 Senior Member

    Joined:
    Apr 16, 2014
    Messages:
    687
    Occupation:
    field technician
    Location:
    northeast pa
    Its in neutral no rpm on dash it worked until it wouldn't restart. it cranks good I'm leaning towards communication issue, switched power to ecm , possibly bad ecm.
     
  4. Bigbert

    Bigbert Well-Known Member

    Joined:
    Jan 2, 2016
    Messages:
    247
    Occupation:
    Consulting Engineer
    Location:
    Germany
    You are right. With system cranking start inhibitor from trans control unit is not the issue. Rather ECU. As far as I remember TCU was fitted in box right hand side of cabine. Possibly ECU is also there. Check all the connectors from that box towards engine. If ECU is around engine check all connectors, clean with air.
     
  5. ianjoub

    ianjoub Senior Member

    Joined:
    Jun 22, 2018
    Messages:
    962
    Location:
    Homosassa, FL USA
    It is always best to star on the last thing worked on. You washed it! Pull apart every electrical connection you can find and inspect, then rinse in WD-40.