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JLG 400CRT scissor lift won't throttle up- help please

Discussion in 'Other Construction/Demolition Equipment' started by tacotory, Apr 26, 2018.

  1. tacotory

    tacotory Well-Known Member

    Joined:
    Aug 6, 2009
    Messages:
    55
    Location:
    Oregon
    Hello-

    I have a couple JLG 400CRT rough terrain scissor lifts. One of them will not throttle up with you activate the movement functions like it is supposed to. It does all the functions, just at an idle.

    I had a mechanic working on it and he said he thought he had tracked it to a bad relay. Unfortunately, he got sick with cancer before he could make the fix and he is not working anymore.

    I looked around and the only relay I could find was the at the back of the engine near the throttle activation box. I replaced that but it didn't fix the issue.

    Does anyone know if there are other relays located elsewhere on the machine, or does anyone have any other ideas as to what may be causing the issue I am having?

    Thank you in advance for any advice!
     
  2. tacotory

    tacotory Well-Known Member

    Joined:
    Aug 6, 2009
    Messages:
    55
    Location:
    Oregon
    A bit more info. I was able to confirm that the actuator that moves the throttle linkage is working fine. I put power to it and it did what it was supposed to do. So just not getting power to the actuator...

    Any ideas?
     
  3. tool_king

    tool_king Senior Member

    Joined:
    Mar 29, 2010
    Messages:
    1,071
    Occupation:
    road mechanic owner
    Location:
    new jersey
    Do you have gas or diesel engine ? Trace the wires backwards .I can send the electrical schematic on it .What is your email address ?
     
  4. tacotory

    tacotory Well-Known Member

    Joined:
    Aug 6, 2009
    Messages:
    55
    Location:
    Oregon
    Gas/propane. The electrical schematic would be a huge help. I will see if I can figure out how to p.m. my email address to you. Thank you very much for the help.
     
  5. tool_king

    tool_king Senior Member

    Joined:
    Mar 29, 2010
    Messages:
    1,071
    Occupation:
    road mechanic owner
    Location:
    new jersey
    How did you make out with your JLG lift ?
     
  6. tacotory

    tacotory Well-Known Member

    Joined:
    Aug 6, 2009
    Messages:
    55
    Location:
    Oregon
    Not good. Still struggling with it. We traced the wire all the way to where it comes out of the lower control box and when we give it power at that location the machine throttles up like it is supposed to. So basically we have been able to determine that there are no breaks in the wire and that the machine isn't sending it the signal. The mechanic I was working with determined that it must be the board. I got a new board and it didn't change anything. He said that the only thing he could think of then is that the board needed to be scanned for codes and/or programmed/ calibrated with the analyzer. Unfortunately he doesn't have an analyzer. I found another guy that does and he is hopefully going to come look at it today.