The JLG 40F Boom Lift Dilemma

[OFF]

I love learning theory of operation:thumbsup. That way you can apply the knowledge to an almost infinite number of problem scenarios. Are schematics of the PQ's in the manuals and are replacement controllers still available? I think mine are "jumpy", or even an all or nothing/on and off action. I'm wondering if these can be electronically serviced….the circuit looks relatively simple, i.e. no integrated circuits or micro parts.

The JLG part number a PQ controller on Racine valves is 1600036. If you Google that part number you'll get lots of hits, some in the under $300 range.
The JLG part number for just the PQ circuit board was 2900453 but that number doesn't seem to exist any more. Maybe NOS somewhere. I had a bunch but I've given them all away to various people in this thread.

 

[od1]

See the next post for the translation.

:Banghead, , :Banghead, :deadhorse,

 

[od1]

Hi all OD1 here, I'm back with another in a long line of 40F Dilemmas

Well I’m back, it’s been a while. I’m OD1 the founder of this blog. I’m still working on my 40F which has developed a new dilemma.

I’ve made some improvements to the throttle and choke and placed 2 new filters at the 40F rear to hopefully relieve the inherent problems with the Bertea valve body, and at the same time added one for the Bang-bang side.

So I finally got the hoses installed thanks to “OFF” who has been there for me through this interior mess.

Okay so I had to pump out the tank to install the new lines and at that time I removed both valve bodies and did a partial rebuild, and added 2 new springs to the Bang-bang valve body. Cleaned everything up and reinstalled. Refilled the reservoir, primed the fuel pump and started the engine which was sitting for a few years now. Kicked right over. Had to deal with a hydraulic leak but that was fixable.

Here’s where it goes bad. No functions, I’m running everything from the ground control. I cut all the lines to the platform and only have ground control. Okay so I thought I’d let it warm up a bit.

So while it’s warming up (I was a little bored) I threw the switch from ground to platform. The engine dies, which is normal, and then I threw it back to ground and it’s running again. Maybe 30 sec. later I do it again. Same response engine stops and then starts. Then it just dies.

I hit the starter button, nothing, choke button nothing. I check the breakers all look good. I didn’t have a multimeter with me. I thought maybe the switch throwing was just a coincidence, maybe the alternator wasn’t functioning and the battery was just dead. I went and got a 4 amp charger and connected it up to the battery while still connected to the 40F, (I’ve done this before) and the charger shorted out.
In the past when you turned the key you’d hear a click, now nothing. The switch that functions the ground to platform seems physically to be in great shape although I did not test it for continuity.

This is what I did so far,

I disconnected the battery, and cut out 2 diodes that I found in the main panel that seemed to go with the ground box. Remember the other box (platform) has been removed and the wires have been pulled out. Did a diode check and they’re like new. I did see 2 or maybe 3 others way up in there but I’m not sure if this is a diode issue.

I’m dead in the water. And I don’t know what else to look for. I’m hoping someone else has gone through this and can point me in the right direction.

Thanks so much for taking the time to read this through. I'm so happy to see that this site is helping so many.

Regards, OD1
:Banghead

 

[OFF]

Hi OD1, one other path current might have to ground is the alternator. Try taking the big power wire off the alternator and see if your drain goes away.

The engine dying probably had nothing to do with flipping the switch back & forth.

Check for continuity between the positive battery terminal and the chassis (ground). It should not have continuity of course....but if it does, start disconnecting wires one at a time until you loose continuity. Start with the large wires, any small wires would have probably melted/burned.

 

[chevythunder25]

Jlg 40

Hello, I picked up what i believe to be a JLG 40 lift.
any idea where the ID tag is ? I am in need of a manual but local dealer won't help with identification tag.

 

[OFF]

Hello, I picked up what i believe to be a JLG 40 lift.
any idea where the ID tag is ? I am in need of a manual but local dealer won't help with identification tag.

Welcome Mr Chevy, I remember the tags always being inside the basket, on the square post right under the control panel. Some where fastened on top of the boom, near the basket end. A few guys on here have never found it, probably the plate fell off or was taken off.
Two more posts will unlock the private message feature, message me with an email and I'll gladly send you the manual set for the 40F

 

[chevythunder25]

Jlg 40

Mr. Off thank you for your reply. I could use the manual it would help. Everything seems to work except the forward and reverse and drive. Previous owner claimed the valves would stick. Boom works up down extends out and rotates good.

 

[chevythunder25]

Jlg 40

Mr. Off thank you for your reply. I could use the manual it would help. Everything seems to work except the forward and reverse and drive. Previous owner claimed the valves would stick. Boom works up down extends out and rotates good.

It is being delivered this morning so the fun will begin

 

[chevythunder25]

Jlg40

Not sure how to PM

 

[OFF]

Not sure how to PM

It's easy with a little help. Left click on my name "OFF". A drop down menu will appear with the choice "Private Message" and a picture of a envelope. Click that, and you're in business

 

[od1]

Hi Off,

Thanks again for your advice.

I started at the alt. and 4 disconnects later the short was still there so I ripped out all the wires that ran on top of the engine. After reconnecting the wires to the starter solenoid I connected up the battery. No short, so I then continued to connect up another solenoid located near the alt. and then the alt, last was the solenoid for the throttle. Seems good. The engine tried to turn over but the battery was dead. It's on the charger now. Tomorrow I'll give it a try.

You were right about the switch! Not related, just weird timing.

The hydraulic tank is just a few inches above add Off, Do you think that could effect my testing tomorrow? I had time to make a brief test before the engine shorted out and there were no signs of life from the hydraulics. Even the Bang-bang was dead, and before that side worked.

Take care!

OD1

 

[OFF]

it should still work even with the oil level well below the add mark Barr, give it a try.

Maybe your starter was so rusty it was staying engaged. Those engines are so noisy it would be hard to hear. That would make a big short and kill your battery.

 

[od1]

That's good to know about the oil. Now I'm wondering about your starter theory. Anyway all the wiring that ran on top of the engine is gone, and away from any direct heat.

Before the engine cut out I could hear the hydraulic oil circulating back into the reservoir. Sounded like an old washing machine. Zero functions working though, not even the bang bang side which worked before I did the rebuild. That worked before without needing a warm up. I'm hoping it's something easy like an air lock, etc. No leaks now though.

I thought I'd run it for 20 minutes and then take pressure readings. If you have any thoughts please let me know. This 40F has been dead now for 7 years now,

Talk with you soon, You're the best ! Hope your rebuild is going well.

 

[OFF]

That's good to know about the oil. Now I'm wondering about your starter theory. Anyway all the wiring that ran on top of the engine is gone, and away from any direct heat.

Before the engine cut out I could hear the hydraulic oil circulating back into the reservoir. Sounded like an old washing machine. Zero functions working though, not even the bang bang side which worked before I did the rebuild. That worked before without needing a warm up. I'm hoping it's something easy like an air lock, etc. No leaks now though.

I thought I'd run it for 20 minutes and then take pressure readings. If you have any thoughts please let me know. This 40F has been dead now for 7 years now,

Talk with you soon, Hope your rebuild is going well.

Morning Barr, sounds like maybe you have a dump valve that's not closing. There should be one dump valve for each valve section, try & locate them all and test then to make sure they are getting power when you toggle a function. The dump valve solenoids are those big silver relays under the rear of the engine mounted on the frame. Hope you weather is holding, it was only 2C here this morning

 

[od1]

Afternoon Off,
It's way warmer here man, but the leaves are falling fast. I just came in and saw this message. I thought the same thing, which only proves my psychic abilities are working. I checked the pressure and it's bad, so the first thing I did is cut the wires to both of those dump valves which were all pieced together and replaced them. I don't know how to test them to see if they're functioning.

Here is the pressure readings, both readings are before and after those new filters. All readings are the same before and after the the filters,

Bertea = 500 PSI at 3/4 throttle, engine screaming 600 PSI
Racine = 2 PSI at 3/4 throttle, engine screaming 25 PSI

 

[od1]

Okay I just reread your post and I see know what you mean, I'm going out now to test the 2 dump valves.

 

[od1]

Forgot to hit reply on that last message that's why the time is only a minute later,

Just came back in, When The key is on both relays engage. That does not change until I turn the key off. When I hit any position switch on the ground control panel nothing changes. Neither solenoid ever goes off until I kill the main power.

 

[od1]

When I saw the low PSI readings I thought maybe a blocked filter, but all 3 material type filters are new, and the one internal that is in the input of the Bertea was just recleaned prior to your nifty 90 deg. adaptor. My other thought is what if I confused the input and the output on those 2 new filters? I don't think I did but if I did would, or could that reduce flow like that?

I thought of switching the bang bang filter to see but that would mean another loss of oil, or maybe even another pumping out of the tank.

 

[OFF]

Forgot to hit reply on that last message that's why the time is only a minute later,

Just came back in, When The key is on both relays engage. That does not change until I turn the key off. When I hit any position switch on the ground control panel nothing changes. Neither solenoid ever goes off until I kill the main power.

yes, those solenoids and the dump valves should be powered when ever ground control is selected. When basket is selected, the dump valve power runs through the foot switch (for safety sake - so you can control things should you be up in the air and one of the functions sticks and takes you for a ride you don't want to go on). When the dump valves are not powered, they are exhausting hydraulic flow back to the tank. When they are powered, they stop this exhaust flow so the pressure can go to the function you need it on. You mentioned a lot of hydraulic type noise, is that still going on? Any chance the lines you added for the filters are directing most of your pressure back to the tank?

 

[od1]

I sent you a message a while back as far as the hose positioning. You thought they looked right. It was the email with the pic's. My thought was maybe I confused the filter housings. Maybe the input side on both filters are reversed? If so could that reduce the flow?

Remember before I added the filters I still had low pressure, but not low like this, almost nothing on the bang bang side, and less than 800 PSI on the Bertea side.

No extreme noise from tank now. Maybe it was air mixed in firing through. Quiet enough now.