JLG 40H Telescope in not working and Starter kickin out after 3 seconds

[bjh101]

The problems are the same from the platform and the ground controls.
This is a JLG 40h from the 1990's it is a Ford dual fuel with Precision Governor. It was rebuilt by JLG in 2000.
1. Starter kicks out after only a few seconds. Sometimes it works fine. but other times it will not engage starter long enough for the engine to start. I can get it to start if I use a wrench to short the solenoid.
2. Telescope in will not work from ground or platform. Sometimes it is fine but 50% of the time it will not work. From the platform I can sometimes get it to go in if I hold the Telescope in switch and each time I step on the foot switch the platform will move in about an inch.
3. When the Telescope In doesn't work the steering is also very slow and the drive motors will not go into high speed.

The mechanic I called said he thought is sounded like a voltage loss causing the solenoid not to open the valves all the way.
I have 12.5 volts with engine off and 14.5 with engine on.
I cleaned all the ground connections, and tightened all terminals. I replaced the ignition switch because it had about a .5 voltage loss.
I have checked all the terminals and can't find any voltage loss.
I have read about changing the trim pot on the governor to increase the kick out starter RPM setting. Evertime I start to do that the starter will start working correctly for a few hours .

I was wondering what the select relays do or if anyone has any other ideas.

 

[OFF]

Welcome bjh101!
Your telescope circuit is very straight forward, there is nothing between the switches and the telescope valve. The telscope valve is on the racine solenoid valve bank, furthest valve from the dump valve (inlet). One wire is red, the other direction is yellow. Check your ground wires on those coils for good continuity. Also make sure your power signal is getting to the valve (the red and the yellow wire). I use very long jumper wires attached to my meter to do this.

On your starter problem, there is a "start lockout" relay in the ground panel. That relay might be weak and not holding any longer than 3 seconds. It's likely either that or the governor control box.

 

[bjh101]

I will test the telescope circuit tomorrow.

I have directions on how to change the trim pots in the governor control box .
but is there any way to test the start lockout relay.

thanks

 

[OFF]

I will test the telescope circuit tomorrow.

I have directions on how to change the trim pots in the governor control box .
but is there any way to test the start lockout relay.

thanks

I think all those relays are the same in the panel. Compare the terminals to make sure and then swap the lockout relay with one of the other relays. If the problem stops, you know it's your relay. if it doesn't stop, it's more than likely the governor box signal.

you could remove the lockout relay and run a jumper wire from terminal #30 to #87 on the socket (black wire to black wire). If the starter still kicks out, you know it's either the starter or your starter buttons.

 

[bjh101]

Well I am finally able to continue this thread. The lift was at a remote location for 6 months but now it is home where I can work on it.
I resolve the starter problem. but still have the problem with telescope in .
I have tested the battery and replaced both battery cables.

Telescope-in does not work consistently. It will have periods when the telescope-in will not go in. When it is not working , each time I hit the platform or ground telescope-in it will go an inch I hear the hydraulic load for about 2 seconds and then it stops.
When the telescope-in is not working the also steering will not work to left unless moving.
I got telescope-in to work a couple of times from platform tonight by hitting telescope-in while steering full right.
when telescope-in is not working the platform level is also very slow.

when the telescope in is working the steering, and platform level work perfectly. When the telescope-in it is not working the steering and platform level are very very week.

When it works, it works from both positions. when it doesn't work it acts the same from both the ground and the platform.

 

[willie59]

But during all these events you have no problem with telescope out?

 

[bjh101]

No problems with telescope out.

 

[willie59]

You've got a very curious problem bjh, one I've never seen before, I'm not quite sure of what to make of it at this point. I'll keep pondering, but I'm at a loss for the moment. :beatsme

 

[bjh101]

I know there is a valve that keeps the boom from coming down when the engine is off. That is the only thing I can think of that makes the telescope in different.

I have another question. On top of the hydraulic tank is a gauge that has a green yellow red sections. when the engine is running the gauge is just past the yellow and beginning into the red.
I checked the hydraulic oil is is clear and full.

 

[willie59]

Yes, the boom lift cylinder as well as the telescope cylinder have a holding valve that prevents the boom from dropping or sucking in when the engine isn't running. But I doubt that's the problem with your telescope as you also have a problem with steering, which has no holding valve.

The gauge on the tank is the return filter restriction gauge, indicates the hyd return filter needs chaning. But again, I can't see that being the problem in this cse.

 

[bjh101]

I looked in the manual and can't find out anything about changing the filter. Is it straight forward?
I live near bestline in shippensburg . I assume I can get a filter from them or do you know a better source.
I have to head to bed. I'll look for your response later. thanks for the help.

 

[willie59]

Bestline in Shippingsburg can provide the filter and service for that machine.

Yes, changing the return filter is easy. The filter housing is located in the tip of the hydraulic tank with a cover held on with 4 bolts. Remove the 4 bolts to remove the cover, however, there is a spring will be pushing the cover when bolts are removed. It's not a lot of spring tension, it hold the filter in place, simply push down on the cover with one hand, remove bolts, then let the cover rise with your hand. You can now access the filter cartridge.

 

[mark3885]

I just came across this thread and I am having a problem with the starting , precision governor start lockout or a relay .
bjh101 what did you do to resolve the starter issue?
I am getting 1.24V on the black wire with white stripe and nothing on the white wire on the same terminal on the starter solenoid , I'm thinking thats way too low to energize the starter solenoid .I don't even get a click , all terminals have been removed and cleaned.

 

[OFF]

I just came across this thread and I am having a problem with the starting , precision governor start lockout or a relay .
bjh101 what did you do to resolve the starter issue?
I am getting 1.24V on the black wire with white stripe and nothing on the white wire on the same terminal on the starter solenoid , I'm thinking thats way too low to energize the starter solenoid .I don't even get a click , all terminals have been removed and cleaned.

Are you getting 12 volts at the starter button? Those starter buttons were notoriously bad. it could be that simple. After that. open the main panel where you'll find about 20 small black square Bosch type relays. They should be marked, locate the start relay. That would be my #2 choice. Download the manual from the JLG web site if you haven't already. Follow through the wiring schematics and check out the trouble shooting section.

 

[mark3885]

I'm getting 12v at the start button and changed the relay , still no go. So could it be the starter lock out relay ? I'm getting 1.24v at the black with white striped wired connected to the starter relay which connects to the red wire on the starter lock out relay , I'm thinking it should be 12v. I looked online and new they go for $610 , are the rebuildable , like through Hindley electronics ?
Sorry about hijacking your thread , bjh101 , jump in , if you need too.

 

[bjh101]

the problem I had was the starter would start turning the engine and then the starter would kick out before the engine would start completely. I installed a tractor universal ignition switch in the ground panel. the new switch has a traditional starter position. I then ran a new wire from the starter pole to the small terminal on the solenoid closest to the starter. Now I can keep the starter engaged until the engine starts. After the engine is warmed up it starts fine from the platform. According to other things I've read, there is an adjustable pot in the governor controller that can be adjusted to keep the starter engaged longer.

 

[mark3885]

Mine has a starter button that will keep the starter engaged until you release the button . Mine is a 1993 40H.

 

[mark3885]

the problem I had was the starter would start turning the engine and then the starter would kick out before the engine would start completely. I installed a tractor universal ignition switch in the ground panel. the new switch has a traditional starter position. I then ran a new wire from the starter pole to the small terminal on the solenoid closest to the starter. Now I can keep the starter engaged until the engine starts. After the engine is warmed up it starts fine from the platform. According to other things I've read, there is an adjustable pot in the governor controller that can be adjusted to keep the starter engaged longer.

The adjustable pot you are referring to, is that in the precision governor starter lock out? This wire you added , is that where the the black wire with white stripe is connected ? So what you did was supply 12v from the start switch to the starter solenoid bypassing the starter lockout. That is what i need to do , a new starter lockout is $610 up to $953.
Off and Willy59 , please respond and help me save $610 to $953. Thanks

 

[OFF]

Something else you can check mark3885 - the starter wire goes through a vacuum switch that acts as a starter lockout. You have a 40H right? Not a 40HA?

Begin at the engine, follow all the vacuum hoses you can see coming off the intake manifold or carburetor. You should see a 3/16" hose that runs off to the chassis or the hood structure and ends in what looks like a common pressure switch with 2 wires on it. Jump across those 2 terminals and see if your problem is solved.

Is your machine duel fuel? The starter wire also runs through the gas/propane toggle switch. Check for power there.

 

[mark3885]

Yes its a 40H , 1993 , I will check the vac hoses and the pressure switch , when I get back this weekend.
Would it be advisable to run a 12v power wire from the starter button to the starter solenoid / relay ? Would I be doing any damage ? I'm only getting 1.24v on the black with white stripe wire from the starter lock out relay. Thanks mark