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JLG T350 towable electric lift won’t go down

fourwheelinj1

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Recently bought a T350 battery lift at auction and everything seems to work fine except the lowering the boom function. When you operate any of the functions you hear the electric motor run. The problem is when you hit the boom lower switch nothing happens. No noise at all. If the boom is low to the ground and you hold the switch it will lower super slowly but no motor engagement. Today I raised the boom up high using ground controls and it would not lower at all. I had to use the manual emergency lowering handle to get it down. Same results from ground controls or basket. No noise no warning trouble lights just does nothing.
 

92U 3406

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Sounds like an electrical issue with that one function.

Do you have the service manual? It should be available for download off JLG's website if you need it.
 

Moonlite

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that unit does not use the motor to lower. just uses coil to open the spool on cylinder block, to lower by gravity.
 

fourwheelinj1

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that unit does not use the motor to lower. just uses coil to open the spool on cylinder block, to lower by gravity.
that unit does not use the motor to lower. just uses coil to open the spool on cylinder block, to lower by gravity.
Moonlite, given that it doesn’t really lower at all do you think that means the coil is bad and not opening the valve? I guess I need to look into testing the coil. I am assuming it is on the valve block?
 

Moonlite

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Moonlite, given that it doesn’t really lower at all do you think that means the coil is bad and not opening the valve? I guess I need to look into testing the coil. I am assuming it is on the valve block?
yes you need to check and make sure you are getting 24 volts to the coil. its mounted on the cylinder block near the base of the cylinder.
 

fourwheelinj1

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yes you need to check and make sure you are getting 24 volts to the coil. its mounted on the cylinder block near the base of the cylinder.
Moonlite, I tested the voltage at wiring harness where it plugs into the coil and got 12.2 volts. I probed the 2 wire pigtail with the positive and negative of my multimeter to get the 12.2. Is the coil 12volt or 24? I also tested the resistance across the coil and got 0 so I am thinking the coil is bad but I am curious about the 12.2 instead of 24volts
 

Moonlite

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should be 24 volts. post your serial number and i will verify. or you can google jlg manuals. they have their parts and service manuals online.
 

fourwheelinj1

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0030006844 is the serial. It is a 24v lift. Did I test the voltage correctly? Both multimeter leads to the 2 coil pigtail wires while the switch is being activated?
 

Moonlite

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your way of testing is ok. have you verified that you actually have 24 volts at the batteries? also verify you have 24 volts at the ground control panel. (e-stop, key switch, up down switch)
 

fourwheelinj1

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Ok so I messed with it more and I was wrong it works fine from the basket just not from the ground control. I am planning to use this thing to hoist some floor trusses up so I need to get the ground controls working also. Since basket works I am thinking maybe a bad toggle switch on the ground control. I am going to pull the panel tomorrow and maybe switch switches with another function and see if that pin points the problem. Thanks for all the help so far Moonlite.
 

fourwheelinj1

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your way of testing is ok. have you verified that you actually have 24 volts at the batteries? also verify you have 24 volts at the ground control panel. (e-stop, key switch, up down switch)
Moonlite I need your guidance. I switched the boom down harness to a different toggle switch and no change still won’t lower down. So it is not the switch. Any suggestions where to look? Works from basket but only 12v going to coil when using ground switch. Everything thing else function just fine
 

Moonlite

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gonna have to trace the down wire from the ground control box to start with. check where the wires go through the turn table. may have to separate the loom.
 

fourwheelinj1

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Nothing yet. Wiring harness looks good from what I could see without really tearing it down. Found another way to get my trusses set so for now it works fine from basket. When I get more time I might look at it again.
 
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