Grove SM4688XT help
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  1. #1
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    Default Grove SM4688XT help

    I have a Grove manlift that has no signal to the throttle solenoid. There is no deadman pedal just an enable button to make the joystick alive. All the motion controls work the lift raises/lowers moves and turns, the engine just doesn't power up to supply hydraulic flow.

    I am looking for ANY wiring diagram for this thing. The joystick functions so, most likely not that, the solenoid works when 12 volts are applied.

    Steve

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    Are you sure its not an interlock...for instance motor wont rev until bucket is clear of the ground.....I worked for a crowd had a fleet of these lifts......nightmare..... like when one wouldnt start to be driven off a trailer 600 miles away.

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    There is no interlock the power enable button is all that inhibits motion, it has a timer. The power enable allows the joystick to raise/lower the platform and move the lift no problem. The engine remains at idle, the joystick should apply power to the throttle solenoid whenever it moves off center. There is a pot that is geared to the X axis and micro switches with cams on the Y axis. There is no single point of actuation for the throttle, it must be a any action powers the solenoid. The throttle power must flow through any axis off center, where and how that power flows is where I am stumped.

    Steve

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    Simple solution may be to speed up the engine idle enough to operate the machine.......I had lots of experience on JLGs,all of it bad.......I couldnt fix something,bosses would get out the service tex from JLG.....he was hopeless,used to feel sorry for the poor guy......one time he put his laptop and test panel on top of a wheel ,then moved the lift and ran over them .....25ton .....Anyhoo,I call it poke and hope fixin.....maybe it runs ,maybe not.

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    The painters used to stand on the top rail and bust the joystick control......thing aint fixable,whole assy must be replaced cost some $600-700.......one time they had a tech out from JLG ,and one a/hole painter gave him a hard time....the tech replaced the self levelling sensor on the bucket 90deg out......soon as the painters pushed the self level,the bucket turned on its side and tipped them out......I got a good laugh out of that....Druggie idiots.

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    Does the wiring from the throttle solenoid go back to a central point or CPU area? Not sure if that's still intact, seems like it would need a relay if its a 12vdc actuated device, that relay could be an issue or then what controls the coil. What you describe makes sense, many parallel conditions requiring more hydraulic flow would cause the engine to rev, and then when all conditions subside, it would drop back to idle...possible timer-off delay in there as well.

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    Matt,

    I agree that a relay may be the issue, I swapped relays and tested them no issue. There is no CPU or "brain" it is strictly electro/mechanical relay logic. One issue is all the wiring is white and is not numbered, the wire for the throttle goes into the relay panel then it is hard to follow.

    The timer delay is working, when you push the power enable it times out with no activity in 20 seconds. When the throttle worked just pushing the joystick off center would rev up the engine.

    The idea that the issue can not be resolved with restoring the throttle control internally has been considered, I really want to solve this problem but, a wireless remote could be a work around. I have wireless crane controls so I am not opposed to them, it just adds another layer of functionality to deal with.

    Steve

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    Good close to this thread,

    I traced the issue to a circuit breaker, the lift now throttles up with joystick movement.

    Steve

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