Jlg 40h lift & swing both out of control.

[Paulanthony]

Have a 2000 40h w/deutz 1011f and pq controls. All of a sudden lifting up and down and swinging are kind of doing there own thing only from the platform. Ground controls work fine. Example: you can lift up then swing and boom will suddenly drop down. You can just step on pedal and may drop or swing without touching controls. I find this strange, unusual and extremely dangerous! I would appreciate any suggestions. I kind of lost on this one. Both controllers were fine till this happened. Thank you!!

[MrKomatsu]

Sounds like a dead short in your harness...probrably at the bend on thr lower side of the platform.
Going up thru the boom section. And when you step on pedal you are provideing power to a already pulled controller handle
in a sense....any one else care to join in?

[Paulanthony]

I did have a rip on the harness right before it runs into the boom. The harness is about 4 yrs old since it was replaced. The rip was taped already, i peeled all the tape off and looked closely thinking that may be a problem. I could not find any breaks in the wires. I will certainly look again and everywhere else i can see on the harness. Do you think if that was the problem it could affect both functions? I did notice in the wiring schematic that these two functions are related. Thanks for the idea! I can use a few more so when i make it back over there i can hopefully figure it out!

[willie59]

It is a possibility that you have a cable problem since two different functions went awry at the same time. But unless you find a failure in the cable, it's difficult to prove cable is the problem, and expensive to simply replace cable just to find out, so it's best to eliminate other possibilities first, namely controllers. It is very odd for two PQ controllers to go nuts at the same time, but not impossible. All three of those PQ controllers has a plug in connector on their harness, if the drive is working proper, meaning, it has a good/proper controller, switch the drive controller with other functions, boom and then swing, see if that controller gives a different result on boom and swing.

[Paulanthony]

I will switch controllers and give it a try. What makes me feel like it wouldnt be the controllers is that everything works fine then all of a sudden the boom will just fall or start to swing. yrs ago i did work at a rental shop and fixed these booms and never have seen this problem. If one problem only i would think it is a break in the harness or a controller. I have been reading the posts before i joined and figured i have a real good chance of finding the problem. Alot of people have a very good knowledge on here ! Willie you sound like you have worked for jlg.. I used to call jlg when i worked for a company with an account and if i couldnt figure it out they always helped me and problem was always solved. Anyway i do appreciate all the help i get from members.. Thank you

[willie59]

Willie you sound like you have worked for jlg

Haven't worked directly "for" JLG, but have been JLG certified on models prior to 2003, have worked on many JLG models, and many other aerial lifts, Genie, Skyjack, and others.

[Paulanthony]

I actually worked for nations rent( now sun belt )for 6 yrs. I was even a certified Jlg tech also. Did genie also. It's been while and lost plenty of knowledge of the yrs. I usually figure it out. But this one is very confusing. Hopefully it's just simple and I just missed something. I hopefully find something stupid and it's done. Thanks again!! I may make it over there Wednesday and I will post the latest. Anyone have any ideas feel free to let me know!

[bobb]

sounds like a harness problem. maybe in the power trac? i would check every inch of cable and the connectors too. i dont like the way they clamp the ends on the cables. i make the wires real short so the clamp goes on the cable insulation.

[Paulanthony]

Sry for not getting back here for a while. I looked at everything possible. Cleaned every wire. I did find 1 wire that showed a very small scrape on it. Very little metal was exposed. The wire was laying in hydraulic oil right behind hyd tank. I don't know if it can conduct like water. I thought the break would be in the platform to ground harness. If this is possible pls let me know. It's been workin properly but sometimes it did for a while anyway. Thanks again!

[mark3885]

I had the same problem on my 40h. I switched the up/down controller with the drive controller and have not had a problem since . I actually like the way the machine works now rather than before. Now I have a creep function on the up / down and swing. The drive , I have creep and high wheel speed.