JLG 600A stuck in turtle / creep mode

Working on my 97 600A with Deutz. It seems that my travel and possibly my control speeds are stuck in either creep mode or turtle (if there’s a difference). Throughout different movements and switchology I can hear the 3 different RPM ranges that the MX manual mentions.

I’m new to this machine and been going over some issues with it. I found what I believe to be the boom level sensor unplugged. I thought maybe this was the issue but after plugging it back in there was no change (the manual states anytime the boom is above the horizon the machine will creep).

Thoughts on the sensor just being bad? Is this switch normally open or closed? Can I jump it for Diagnosis purposes ONLY? Or should I look in some different places?

Any help would be much appreciated!!!

Check your proximity switches. Sounds like 1 is stuck.

You have one limit switch on the boom extent retract and one for stowed drive that control drive speed control. One could be stuck or bad. Do you have a hand held analyzer ?

Thanks for the replies. I have visually inspected all of the switches and they seem to function correctly (externally).

I do not have an analyzer, will the analyzer work on a 1997?

I have attached an excerpt from the maintenance manual regarding the limit switches. Which switch would be the one possibly limiting the travel speed?

Check your horizontal limit switch. And the boom extend retract limit switch. Those are the two that tell the machine your out of trasport mode and to reduce drive speed. Are all your other functions stuck in creep to ? Like lift, basket rotate etc. Or just drive when stowed ?

Txhayseed said:

Check your horizontal limit switch. And the boom extend retract limit switch. Those are the two that tell the machine your out of trasport mode and to reduce drive speed. Are all your other functions stuck in creep to ? Like lift, basket rotate etc. Or just drive when stowed ?

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I will look further into the switches. I know the boom extend/retract switch is working because I get the 1000lb/500lb platform limit light at the platform control panel. Which switch is the “horizontal”?

I’m new to the world of boom lifts but to me everything seems slow. It’s as if the speed rheostat on the platform control panel makes no difference when operated.

Thank you.

The platform dial controls functions like basket tilt, rotate , jib etc.. the rheostats them selfs do fail and its common. I replace alot of them from people wrenching down on them and simply breaking the internal works. I think your on track with the limit switches causing your stowed drive speed beeing slow.

Txhayseed said:

The platform dial controls functions like basket tilt, rotate , jib etc.. the rheostats them selfs do fail and its common. I replace alot of them from people wrenching down on them and simply breaking the internal works. I think your on track with the limit switches causing your stowed drive speed beeing slow.

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Okay, I am pretty sure I have the limited travel speed pinpointed to the lower horizontal limit switch seen in the attached picture. It seems to me that it’s always activated with the way it’s currently mounted.

I took it off and I get a much faster travel speed after I turn the control speed rheostat to anything other than turtle.

The rheostat does however seem more like an on/off switch vs. the way a rheostat “should” work. Whenever I dial the rheostat to anything other than turtle the green snail light comes on and stays on; this doesn’t seem normal to me?

How should the lower horizontal limit switch be mounted?

Thoughts on the rheostat being worn out or wired wrong? Should this rheostat have any control of travel speed at all (its a 1997)?

Thanks!

The rheostats is like that even when its new. It really does not ever seem to change much unless you have it dialed one way or the other. There is really not a middle ground.

The limit switch should activate as it rotates around the boss. The pin boss is actually the eccentric that actuates the switch. Id open it up and see if the plunger is working or broke. We replace alot of limit switches. The get stuck/ broke and contacts just fail.

Txhayseed said:

The limit switch should activate as it rotates around the boss. The pin boss is actually the eccentric that actuates the switch. Id open it up and see if the plunger is working or broke. We replace alot of limit switches. The get stuck/ broke and contacts just fail.

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I got the lower horizontal limit switch working. I adjusted it a bit but I think it may have just been jammed. I now get a much faster travel speed.

Do you have any insight on the control speed rheostat? Why does the green snail light come on and stay on whenever the rheostat is moved out of turtle?

If your green light is not kicking off when you turn the rheostat it might be time to replace it. I would however remove the nob and make sure its actually turning the shaft on the rheostat itself.

Txhayseed said:

If your green light is not kicking off when you turn the rheostat it might be time to replace it. I would however remove the nob and make sure its actually turning the shaft on the rheostat itself.

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The green snail light is off when the rheostat is turned all the way CCW and “clicked” into creep mode. Isn’t this when the green snail light should come on? Then, once “clicked” out into turtle or anything all the way up to rabbit the green snail stays on and control speeds really don’t change at all. The only difference is that I have fast travel speed anytime the rheostat is “clicked” out of creep.

Does any of this make sense?

Another issue I noticed, the platform operates basically all of the controls regardless of key selection on the main control panel. The only thing that won’t work is the kill switch in the platform. Any suggestions on where to start on this issue? I swear once I fix one problem another pops up.

Thanks!