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spankyjr1, Journeyman
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I have a JLG n40e that will not operate any of the controls

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I have a JLG n40e that will not operate any of the controls from the main motor. The drive works and the basket sway works, nothing else. I've cleaned the changeover and the main contactor, but it did not solve the problem.
Submitted: 11 months ago.
Category: Industrial Equipment
Expert:  Michelle-Mod replied 11 months ago.

I'm Michelle and I'm a moderator for this topic.


I was checking to see if you had already found your answer or if you still needing assistance from one of our professionals?



Thank you,

Customer: replied 11 months ago.

I'm still waiting for an answer at this point.

Expert:  Michelle-Mod replied 11 months ago.



Expert:  spankyjr1 replied 11 months ago.
Hi and welcome Please do not rate until all your questions are answered.
Use reply to expert link.
Thanks spanky

Sorry for your delay

I have a couple questions if you don't mind.

Does everything work correctly from basket controls?

Do you have a digital volt ohm meter?(DVM)

Have you load tested batteries?

Let me know
Customer: replied 11 months ago.

No. The only things that work are the basket side to side (not the tilt) and the drive and steering work. Nothing that is driven (supplied oil) from the (what I'd call) the primary motor and pump will work. When the foot pedal is pressed, I can hear the initial contactor kick in, but then the switches don't work (to start the motor). I can hear the valves for the individual controls working, but there is something that won't run the motor. It was sporadic at the start, and I could override from the ground controls, but now it doesn't work from there either.

I have a volt/ohm meter. I have 50 volts being supplied to the system.


I believe the batteries are fine since they will run the drive wheels, and they require the most juice.


My suspicion is the DC motor controller, but I have no way (or I don't know how) to test it.

Expert:  spankyjr1 replied 11 months ago.
Thanks for info.

The reason I asked about batteries is if battery voltage drops below a certain limit it stops all functions accept drive and rotation.
Even if supplied with shore power if they are not being charged.
The reason why is so you can get it back to charge or loaded for transport.

So first thing is load test batteries.

I'm going to gather some more info so you can test some things if bats are good and get right back to you.

Hold rating until were done please.

I'm usually online from about 6am -6 pm C.S.T.

Customer: replied 11 months ago.

I don't have a load tester, but I'll track one down and see what I come up with.

Expert:  spankyjr1 replied 11 months ago.
If you don't have one or can't borrow one most auto parts will load test for free,but you have to bring to them.

You can also purchase one from local auto parts or on line like Harbor freight,you don't need a expensive one for the limited use you will need it.
They do come in handy.

You don't need to take off cables just do one bat at a time with shore power off.
Then plug in and see if voltage rises.

Let me know how it goes.
Expert:  spankyjr1 replied 11 months ago.
Okay you basically have 3 sections that separate one system from the other they are


electrical control low voltage amps

electrical supply high voltage amps

Your contacter gets control voltage to close which connects supply voltage to motor,
we know your control is working because contacter closes but pump not working.

You need to check battery voltage before contacter first,then check power out of contacter once it closes,so you should now have battery power on both sides of contacter,then check for voltage at hydraulic motor while contacter is closed,if you do have power,and ground at motor,then motor is bad.

If you don't have power and ground to motor with contactor closed there are two fuses in between contactor and motor, one 200amp and one 80 amp.Check for open circuit.

Cause of why these fuses will blow is bad motor,low battery supply voltage.
(Bad battery)

So you do need to load test batts but while your waiting you can check fuses.

I'm usually online from about 6am -6 pm if you have any questions just let me know.
If you have no more questions Please ether accept or rate ok or higher.
There is no extra charge for this and is the only way I get credit for my time.

Thanks and have a great day spanky

Customer: replied 11 months ago.

I had already tested both fuses, and they are fine. I load tested the batteries and they are all fine, not new, but fine. As far as I can tell, there are two contactors that control the system. The first one works with the pedal switch, and that one appears to close. The second one does not close, or at least does not appear to close, hence my suspicion that it's either the contactor (which I cleaned and the solenoid appears fine) or the motor controller. I'm not an electrical expert, but my guess it that the motor won't work until all the voltage is supplied to the motor. Once the first contactor closes I have 12 volts, but the second never closes to get to the 24 volts the motor needs. (I think it's a 24 volt motor even though it's a 48 volt system)

Expert:  spankyjr1 replied 11 months ago.
Okay then it on control side .

Do you have voltage at contacter to close it?

I will look at wiring to see what wire you need to check at the contacter that's not closing.

Be back
Expert:  spankyjr1 replied 11 months ago.
Are you getting any codes?

Here is how to get codes.
SECTION -3120861–JLG Lift–-52. General Features. a. Diagnostics. To obtain flash code, depress foot switch and repeat operation which caused fault. After fault occurs, maintain foots witch and function position and
read flash code.
NOTE: Flash code repeats after pause.
Flash codes are as follows: LED On - Controller Operational.
LED Off - Internal Fault or Power Not Turned On.
Hydraulic motor is 48 volts.
Drive motor is 36 volts.
Control is 12 volts

Just let me know if your getting any flashes and how many.

Customer: replied 11 months ago.

5 flashes.

Expert:  spankyjr1 replied 11 months ago.
When you checked codes did you try a function that is not working?

Flash 5 says for drive contacter and drive would be inhibited.

You said drive was all good correct?

Just need to make sure.
Customer: replied 11 months ago.

Yes, drive works fine. I looked into the 5 flashes before and that only led to my increased confusion....that's when I tried this service.

Expert:  spankyjr1 replied 11 months ago.
There are some things we can't over look that is why I'm asking so I don't give you bad advise.

It seams as you have experience, I don't want to sound insulting just trying to get to bottom of trouble.

Have you checked for control voltage to pump contacter?
If not check to see if you have voltage, have someone try a function while you check for control power,if you have no voltage and since you have no other codes I would replace motor controller.

Have you tried manually closing pump contactor just to make sure everything works?
If not, manually close contacter and see if it works, if it does I would replace motor controller.

If you had any limit switches keeping it from working you would get a different code.
If you had a open wire going to pump contactor you would have a different code.

I don't expect that you will have voltage at pump contacter to close it but just need to check before replacing.

This question will remain open even after you rate for about 30 days, so you can always come back to question.
Just bookmark page so it does not get lost.
There's no extra charge for follow up questions

Customer: replied 11 months ago.

Part of my confusion stems from the fact that there are 2 contactors that look like they supply power to the pump wire, the by-pass and the changeover. When I push the pedal, the main contactor closes, which means that one is working. (otherwise nothing would work). I took the by-pass and changeover apart, cleaned the contacts and reinstalled them (the contacts were corroded, so I thought I found the issue...) The reason I stated that I thought the controller was bad, is because these contactors weren't closing. There are two wires (obviously) that run from the controller to the solenoid on the contactors...what voltage should I be reading to these? Can I test resistance across this solenoid to see if they're good? If so, what should I be getting?

I'm just trying to make sure that the controller is what's bad...a new one is $1k.

Expert:  spankyjr1 replied 11 months ago.
You can check for open coil or ohm out.

Also short to ground.

The control voltage will be the same voltage and resistance as other contacter.
I would expect it to be 12v or 24 v. but will be the same as the one that is working.

The manual or wiring diagram does not give me resistance of coil,if it is not getting any voltage it is not the issue and does not need to be checked.

I do expect it will be no voltage to coil.
I don't expect it will be low voltage or open voltage otherwise you would get a different code.

The contacters are not closing because they are not getting control voltage to close or you should be getting a different code.

The one is really not a bypass, it is for when two functions are used at one time it speeds up motor, so goes from 36v to 48 volts changing amount of flow.

Only one contactor will close until it needs more flow and motor controller calls for more.

We are just checking to make sure it is the controller,if you have no voltage at either contactor while using a non working function.
That power comes from controller.
If it was a input going to controller it would be a different code or another code.

Thanks spanky

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Satisfied Customers: 1672
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