1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

JLG 450A 3 Functions not working

Discussion in 'Other Construction/Demolition Equipment' started by timtimbutler, Feb 27, 2016.

  1. timtimbutler

    timtimbutler Member

    Joined:
    Feb 26, 2016
    Messages:
    5
    Location:
    NC
    I have a 2000 model JLG 450A, Early serial number. Anyway, I bought the item recently at auction, and have fixed most of its problems. I still however have three functions that do not work.
    -Basket level up and down
    -Extension in or out
    -Basket pivot. Right or left.
    I can activate the function from the basket or the ground and have active coils, but no movement. I can hear the pump slightly labor under load, but no movement. Any ideas.
    Tim
     
  2. willie59

    willie59 Super Moderator

    Joined:
    Dec 21, 2008
    Messages:
    11,885
    Occupation:
    Service Manager
    Location:
    Knoxville TN
    Welcome to HEF timtimbutler. :drinkup

    It sounds like your having a problem with the dump valve for the bang bang functions. Each of those toggle switches are double pole, the terminals on one side work the function valves, up/dwn, left/right, in/out. The terminals on the opposite side of the switches power up the dump valve, should be a red/white wire. Locate the main dump valve relay (R10) and see if it's sending power to the dump valve when you flip any of those switches. If it is, locate the main dump valve and make sure the power from the relay is getting to it and that it has a good ground.
     
  3. timtimbutler

    timtimbutler Member

    Joined:
    Feb 26, 2016
    Messages:
    5
    Location:
    NC
    Thanks for the advice, Willlie59;

    I checked the relay and the coil for the Main Dump valve, and found it to be working properly. The relay is getting proper voltage, and further activating the Main Dump valve. I further verified by operating a working function that also activated the Main Dump and have the same results.

    You mentioned the Bang Bang function, I don't know anything about that, can you explain what that is and how it works.

    Tim
     
  4. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    Thats odd I also have a jlg bought at an auction recently...I fixed wiring harness issues it worked fine for 50 hours...then poop....we checked seem to have hydraulic problem with just half the functions...an eazy check on the solenoids is check for magnitizm...we are ready for a guage...but if anyone can explain how these things work together it would help...HELP!
     
  5. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    Timtimbutler....I would bet your stering Left and right does not work either....that would mean we have same problem...also the forward and reverse drive works fine..sound familiar
     
  6. timtimbutler

    timtimbutler Member

    Joined:
    Feb 26, 2016
    Messages:
    5
    Location:
    NC
    Willie,

    That is where I am stuck, my steering works fine. If I am reading the schematic right, the steering works from the same pump source as the non working functions. I think we have a similar problem.

    I hope one of us figures this out soon.

    Tim
     
  7. willie59

    willie59 Super Moderator

    Joined:
    Dec 21, 2008
    Messages:
    11,885
    Occupation:
    Service Manager
    Location:
    Knoxville TN
    That's old JLG terminology. There are basically two types of controls, proportional and bang bang. Proportional is the drive, boom up/dwn, and swing, those operations are proportional to the degree the control lever is moved. Bang Bang describes functions that work with toggle switches, bang on, bang off, it's just an old JLG term for toggle switch controlled functions and valves.

    True, but not entirely with proportional solenoid valves, they work with Pulse Width Modulation (PWM), and some PWM coils don't work with full 12V so if you put 12V on them to check magnetism it will fry them. I don't think the proportion coils on these machines are less than 12V, just saying one needs to be careful putting full system voltage on a PWM coil, that's all. ;)

    Drive fwd/rev works from a different (hydrostat) pump than all other functions of the machine. Boom up/down and boom swing work from a gear pump feeding P1 port on main control valve, all other functions work from another gear pump that feeds P2 on main control valve.

    Yes, you're reading your diagram correctly. When you posted earlier that you verified the main dump valve was working because other functions that use the dump valve work. I thought "what, his steering works?", to which I was going to ask but you beat me to it to confirm. Ok, knowing this, I'm going to have to do some more noodling in my head. None of your toggle switch functions work from platform or ground, but your steering works, correct?
     
  8. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    well I was not applying 12v just operating the grd function and checking for magnitizm...meaning it should be pulling the spool one way or other...and I follow the P2 gear pump....I was thinking the main relief has blowed out maybe?...my next step was to get a pressure gauge ...it seems like the pumps working but its not building pressure...any thoughts captain?
     
  9. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    there is a type quick connect at G2 , similar to a pressure washer tip accept with a center plunger...I can't seem to find a female fitting to put my gauge on it for a PSI test..any clues?
     
  10. timtimbutler

    timtimbutler Member

    Joined:
    Feb 26, 2016
    Messages:
    5
    Location:
    NC
    Thanks for the Bang Bang explanation. I completely understand what you are describing.

    It is a nice day, so I hooked up a pressure gage to the P2 port, (the functions I am having trouble with) Just to verify the pressure from the source. I have plenty of pressure to work with, although I have all the individual function pressures out of whack, I turned each of them up, to see if I could get some movement. anyway, The steering that does work, is maintaining about 2k during moment. The non working functions where maxing out my 3500 LB PSI gage when movement was requested. Still no movement. I am starting to think that I have a blockage in the manifold.

    Question, Do the sequencing valves work the same direction for the functions I am describing, is it possible that the steering takes a different rout then does the basket functions?

    Question, is there a second valve like the main dump valve that is a built in safety, as my non working functions all are near the basket?

    Thanks in advance
    Tim
     
  11. willie59

    willie59 Super Moderator

    Joined:
    Dec 21, 2008
    Messages:
    11,885
    Occupation:
    Service Manager
    Location:
    Knoxville TN
    I wish I could tell you the part #, unfortunately my head is full of over 50 yrs of numbers. Most hyd hose shops that have various fittings as well will have that quick coupler, of course you would have to remove the male part of the coupler from the manifold and take it with you so they could match the female to it. I might be able to get a part # off of one of mine when I get to work tomorrow.

    I think your sequencing valve is working proper because the steer is working. You can sort of verify that by plugging your test gauge into P2 (actually, the test port is G2) and powering up the dump valve. When you do that, if the sequencing valve is working correctly you should see somewhere around 230 PSI on the gauge.

    Yes, the steering and bang functions share the sequencing valve for those functions, but the steer does take a separate route, one all by itself, the bang functions follow a proportional flow control valve, and that's the next thing I'd look at. When you work a toggle for one of the bang functions at the lower controls, make sure the proportional valve is getting power and that it has a good ground. If it does, I'd pull the proportional valve coil and cartridge and swap them with the same proportional valve that works boom up/dwn or the one that works swing, then try one of the bang function toggles at lower controls.
     
  12. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    it looks like steering has its own feed through a .045 orifice........ Willie 59 Im having trouble with the symbols labeled A,B,C,D...can you id them...it makes more sense...thanks
     

    Attached Files:

  13. willie59

    willie59 Super Moderator

    Joined:
    Dec 21, 2008
    Messages:
    11,885
    Occupation:
    Service Manager
    Location:
    Knoxville TN
    A: the proportional valve for the bang functions. It's a "variable speed control" of functions that work via a toggle switch.

    B: Sequence Valve, at least as JLG decides (and has for many years) to use that hydraulic term. It's actually more of a pressure regulating valve.

    C: the Dump Valve. Normally open, dumping oil from the gear pumps until you power it up and direct oil to functions.

    D: the Main Relief Valve, typically set at a higher pressure than all functions it serves. A last stop gap if all else fails, dumps oil in the case that everything goes awry.
     
  14. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    We just checked the dump valve coil and found it to be open ...this would fix all ... ordering from GCiron.com they seem to have it all covered.
     
  15. timtimbutler

    timtimbutler Member

    Joined:
    Feb 26, 2016
    Messages:
    5
    Location:
    NC
    Sorry for my absence, my day job is working for the Government and I cannot access this forum from my Government PC.

    I have validated that my proportional valve is working, but I still don't have the functions mentioned. I went back through the safety switches, and verified that my two boom limit switch's are working, but my metal sensing switch near the basket is not. I hope to get some test equipment on the subject this evening, and fix that switch, but according to the manual, that should only effect two functions. (boom up, and basket level down)

    The book mentions that I my cut out relay should be affecting those functions, but I don't know where this relay is. any idea??

    I will let you know what I find.

    Tim
     
  16. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    in what way is the proportional valve working.....I thought for sure it would be bad (by the symptoms)....is there pressure on G2 (P2) and the spool is magnetized?...I have to what till friday when parts arrive to know for sure on mine...turns out part numbers did not match for coil so I tracked down another seller (clearwater Hydrualics) and bought coil that had same numbers and looked alike too
     
  17. willie59

    willie59 Super Moderator

    Joined:
    Dec 21, 2008
    Messages:
    11,885
    Occupation:
    Service Manager
    Location:
    Knoxville TN
    Yes, just how did you verify the proportional valve is working if the functions still don't work?
     
  18. bigboytoy

    bigboytoy Well-Known Member

    Joined:
    Feb 20, 2013
    Messages:
    91
    Occupation:
    near retirement Pipe fitter
    Location:
    Terre Haute, Indiana
    It turns out the dump valve was the culprit $20 item....I just wish I would of consulted sooner dumb mistakes cost me a lot more...thanks willie59
     
  19. Donold

    Donold Member

    Joined:
    Apr 17, 2018
    Messages:
    23
    Location:
    Pittsburg
    Greetings, I found this thread to be helpful. I also have an early 450A (Ford dual fuel) with several functions not working. It will not swing, the basket level or pivot and the extension in and out. The unit will drive, steer and it will go up as well as back down. The non working functions will work if I select a working function in concert with a non working function. I changed the dump cartridge and swapped with a coil that works a function properly even though I could see movement in the shuttle with the valve removed. This did not change my situation. When I energize pin 14 I get 3K psi at G2. The manual tells me this should be 230 – 325psi. It has me pulling out my last two hairs.
     
  20. willie59

    willie59 Super Moderator

    Joined:
    Dec 21, 2008
    Messages:
    11,885
    Occupation:
    Service Manager
    Location:
    Knoxville TN
    Need to know S/N and if it does the exact same thing from ground controls