Hi I have been working on my 980H for a few months now trying to get it right for the spring season. i have asked a few question on here before about it. And I could use some more help. serial number is JMS03132 Im having problems with the loader controls. They usually work fine but some time they stop working completely and random start again and make it really jerky to load with. usually tapping the brakes a few times get the controls back. turning th command steering often makes me loss the hydraulics. so over the last months i have replaces all the suction hoses and o rings. double up on each hose clamp. replaces the pilot pump. replaced the lockout solenoid, replaced the brake accumulator priority valve. nothing has helped besides the pilot pump. that has helped on start up to get brake pressure up immediately when cold. So now i finally broke out the gauges. I have the pilot test port hooked up and have a nice hose with the gauge set up so i can see it out the windshield and watch it while loading. pilot pressure gets up to 500psi like its supposed then drops to zero and bounces around all back the fourth pretty much randomly and at all rpms. turning usually makes it drop to zero. and hitting the breaks turns bumps it up usually but sometimes it doesn't. i can post a video of the gauge if it will help. when you turn the machine of the gauge sits at like 300psi i tried turning up the pressure regulating valves up buy the pilot test port.. that didn't seems to make a difference. So any more ideas what to throw at this machine i really can't think of anything else. all help is greatly appreciated, Thank you Jake Harrington
There is a solenoid on the control valve that locks out and implements pilot pressure. That solenoid is controlled by a switch on the armrest with the hydraulic controls. Sounds like you have a wire that is broken and loses contact when you articulate the machine. Someone here with more access to cat information than me can help you better with this.
Also keep in mind that the pressure in the loader arm lift circuit supplies pilot pressure when the machine is not running so any time the loader arms are off the ground you will have pilot pressure coming through a shuttle valve from that. Try testing with the loader on the ground. I had a customer with a weak pilot/brake pump that would always leave the loader arms up overnight so on cold startup he would have pilot pressure.
Mobil tech that makes sense actually i did not know that. Maybe i will keep the arms up for the next few days to ensure no air gets in the system. and paul i was thinking maybe a bad wire but that wouldnt explain the pilot pressure dropping i dont think. The lock out solenoid is after the pilot test port. So with the lock out on or off the pilot pressure shouldnt change? Im really not familiar with the system so please tell me if im wrong. Also in with the lock out button on the armrest in the off position so the arms cant move, i cant seem to make the pilot pressure drop low. Stays between like 500-350 driving around turning and stomping on the brakes. Does this help?
Commenting on your three points in order that you wrote them above. 1. The pressure from the bottom end of the lift cylinders is bled into the pilot system. It's not a case of getting air in, the oil from the lift crcuit is fed into the pilot controls when the bucket is in the air. As MT explained - so that the bucket can still be lowered if the engine ever fails and there is no oil being supplied by the pilot pump. 2. Yes it would. If the signal from the switch goes to "Locked" when the switch in the cab is actually in the "Unlocked" position the first thing that will happen is that the pilot system operation is cut off. That sounds exactly like what's happening to you. 3. Again more confirmation that there is likely something amiss in the signal from the Implement Lockout Switch. Once you have it set to the "Locked" position then whatever might be happening in a wiring harness or connector somewhere will not cause the "lockout switch status" to be constantly changing from Unlocked to Locked and back again as far as the machine electronics are concerned. I thought I sent you the Electrical Schematic for your machine. If not please let me know. Sounds like you may have some wire tracing to do. EDIT: I just looked at the Electrical Schematic and the Implement Lockout Switch has both N/O & N/C inputs to the Implement ECM. If either of those inputs goes AWOL = no pilot system. (There may be other inputs into the Implement ECM from that same switch, I didn't check that closely)
Nige can you send over that electrical Schematic? Is there a way i can hot wire or jump out the lock out switch? Atleast for testing purposes? Because i really dont need to lock the arms ever. Im going to bring my meter out today and see if the lock out signal varies when i turn the machine at all.
Electrical Schematic sent via PM. You can't hot wire or jump the switch because in the signal side of it there is no power. There is a "digital signal loop" for want of a better word between the switch and the ECM. If you locate the switch (Page 17 Grid j-7) it has 3 wires on the top half of it, E918, 953, & E917. If you follow those wires to the ECM you'll find that 953 is a common Digital Return. The schematic shows the Lockout switch in the "Locked" position. So what the ECM is must see simultaneously is continuity between Pins 15 & 14, and at the same time an open circuit between Pins 15 & 13. Put the switch in the "Unlocked" position and the contacts reverse. Continuity between Pins 15 & 13, open circuit between Pins 15 & 14. If for some reason one loop changes state from N/O to N/C or vice versa and the other one does not, the ECM will default to the non-operational state for whatever is the circuit controlled by that switch. My opinion is that this circuit cannot be tested by opening up connectors, it would have to be "back probed" usging spoon-type ends on a DMM. Having said that it might be well worth your while to open up every major harness connector between the Lockout Switch and the ECM, clean them, and check for corrosion.
Figured it out. I switched the primary and secondary pilot pressure regulators with each other and its fixed.. kinda drifts a ton but once i get the new primary and put the secondary back where it belongs i should be up and running
Ok turns out thats not the problem. With both primary and secondary reg valves replaced the symptoms were just as bad as originally. with the two new valves switched and in the wrong position it was ok except for when the bucket was on the ground. With the buck on the floor pilot pressure would drop to zero.... Then the tilt stopping working today. Then started to work again .. now everything has stopped working. No loader arm functions at all. Plugged it into cat ET again.. still no codes and all the tilt/ lift lever respond and send amperage to the solenoids. also all 4 tilt/ lift solenoids have been replaced at on this machine at somepoint as i can tell by the paint.. Shuttle and sequence valve are on order of Monday morning. Hopefully with every valve in the pilot assembly replaced nothing else can go wrong
Has anything been calibrated yet..? Control levers, Lift/Tilt solenoid valves, that kind of stuff..?
If I can just throw this in from the sidelines; On top of the pilot section of the MCV there are two screens, highlighted 59 in the picture. I've only ever seen them get blocked following a major failure or someone getting careless about cleanliness when changing hoses, but when they do get blocked the reduction in flow can cause weird problems.
I havent calibrated anything in about 2 months. I did it when i first bought the machine to when i replaced the tilt sensor i will check those screens this morning also. I havent touched them yet
Based on Cmark's info above I'd suggest to look at those screens as a first step. Because you changed the regulating valves you should really do a recalibration of the all the main control valve operating functions, but that would be after you've been into the screens not before.
Does anyone know what the shuttle valve and the sequence valve? And how they operate? Also im only getting 3.4volts to the lock out solenoid. Shouldnt that be 24v? Or is it a lower voltage from from ecm
Sent you a PM with docs regarding the valves. Have you tested the coil resistance.? Spec is 32.6 +/- 1.6 ohms. Are you testing voltage with the solenoid disconnected from the machine harness or are you back-probing it with everything hooked up.? This is what the SysOp says ............ "The solenoid valve (hydraulic lockout) is an output of the implement ECM. The solenoid valve will disable the pilot hydraulics in failure mode. The solenoid valve (hydraulic lockout) will enable the pilot hydraulics when the solenoid valve is energized by current from the implement ECM. The solenoid valve has a 2-pin connector. One contact receives power from connector contact J1-8 of the implement ECM. The other contact joins together with the other solenoid valves and returns to connector contact J1-7 and J2-3 of the implement ECM. Pin J1-40 supplies power to pin J1-8 within the implement ECM. If the input to J1-40 does not have battery voltage then the solenoid valve will not be energized. " I suggest that you go looking on ECM Connector J1, Pin 40 for battery voltage (to machine frame ground). Then test the voltage between Pins 7 & 8 of Connector J1 with the machine electrics energized, engine running at Low Idle, and the Implement Lockout Switch in the Unlocked position.
Thank you that pin information is exactly what i was looking for. I will do that today. And when i was testing the volt to the lock out solenoid i was doing it with the harness disconnected
You need to be testing with the electrical connectors in place, not disconnected, unless the testing procedure specifically states otherwise. Try to get hold of a pair of “spoons” for the ends of your DMM leads. From memory the Cat Part Number is 7X-1710 for the pair, or 1708/1709 for individual red/black leads. They won’t be cheap, even if you go aftermarket.
I ohmed out the h717 and h716 wire to from the ecm connector to the lock solenoid plug. All was well. 27ish bolts goin to pin 40 and pin 1 and pin 2 was a good ground as well at the ecm plug. Had a friend come over with a set of spoons and he stuck them in the ecm plug at pins 7 and 8 for the lock out circuit and we got 2.4 volts. According to SIS we needed 2.5 volts give or take. so that all tested fine. And still no movement. My friend had a set of 4 new pilot position solenoid so we swapped one out and the dump started to work the. Swapped the rest and they all worked. Now the bucket and arms move again. But the pilot pressure is still jumping around everywhere. Basically im back to exactly where i started.
Your 2nd statement is not correct. With the engine running and the lockout switch in the Unlocked position you should be reading system voltage (24+) between Pins 7 & 8 of the ECM connector J1 if you back-probe it.
When we back probed it with the connector at the solenoid both plugged in and unplugged it read 2.4-5 so that could definitely be my problem then. But my question is after all this i ran a hot and ground from the start direct to solenoid so with the engine running like 27 volts and still no difference. So can i rule that out or not yet? also what do you think can be causing my low voltage between 7and 8?
Also i forgot to mention this. I hooked up a second gauge today after we got the bucket moving. I hooked it up to test the pressure of the pilot pump goin to the brake valve. It gets to about 2100psi and then drops as the same time as when the pilot pressure up by the valves drops and spikes back up when you touch the brakes. Exactly like the pilot pressure except the pilot pressure is only at 450-500 psi
It cannot be ruled out it the possibility of an internal fault in the ECM. You said you borrowed some pilot position solenoids for testing. Your friend doesn't happen to have a 980H Implement ECM you can borrow does he..?
i will chase one down tomorrow I'm sure i can find someones to borrow since nobody has any work right now.
You need to get one as close as possible to what you have right now. If it can be from another JMS-prefix machine so much the better, it really needs to come from another 980H at the very least If it's not from a JMS machine, post the S/N it's coming from and I'll take a look to see how compatible it's likely to be.
Ok sounds good I appreciate it
I haven't tracked down an ecm yet. I did buy a new shuttle valve today and tried that. It made no difference. I brought a mechanic in. and he went over it. he thinks that all the electrical stuff checks out and thinks the problem is the brake accumulators are shot. he wants to try recharging them tomorrow Any thoughts?
It's worth a shot. Try a quick and dirty test of the accumulator efficiency. Start the engine and run at half speed for a couple of minutes to allow the accumulators to build up charge. You may even be able to hear the pump change note when they are fully charged. At that point stop the engine then afterwards turn the key back to the ON position. Press the right brake pedal to the floor then release it. Keep doing that, counting how many brake applications you make until the low brake pressure warning sounds. If the warning sounds in less than five cycles of pressing the brake pedal then the accumulators need recharging.
I can tell you already before i even get back to the machine the alarm will sound in probably 3 pumps of the brake pedal. What would you say a perfect accumulator amount of pumps are for a new accumulator? and how hard is it to recharge then myself? I can definitely get my hands on some nitrogen cylinders?
Sounds like the accumulators are down on precharge. It's not the nitrogen that will be the problem, it's the tooling that is needed to connect the nitrogen cylinder to the accumulator. Did the mechanic who was at the machine today say he had that tooling..? I sent you a PM.
He said he has everything just not sure what its all going to cost. Also not sure if its going to work. He thinks the accumulators will probably going to have to be replaced if they dropped the charge. Sounds like its gonna get expensive really fast if he is gonna be charging then replacing and then recharging and this might not even be my problem
These are piston-type accumulators and they work in a very simple way. Generally speaking they are very reliable. Also they are easily overhauled - if they need to be that is. First thing to try would be a nitrogen gas recharge. I would say that in 99% of cases that would be all that was required. If they do need to come apart and be re-sealed a kit is available. Parts manual page on the way. Also this is potentially a safety issue. You need those accumulators working correctly in order to have a safe, correctly operating brake system.
My thread on cat cylinders shows resealing the accumulators these would only hold one pump of the brake pedal I had charged them a few times last year to keep going until the off season if oil comes out the Schrader valve on the bottom needs reseal for sure HeavyEquipmentForums I got my nitrogen charging setup on ebay around $150 no regulator on the tank
https://www.ebay.com/itm/KENT-MOORE...869805&hash=item44353447cf:g:WncAAOSwRLBcW0rE https://www.amazon.com/Accumulators...ccumulator+charging+kit&qid=1586020016&sr=8-3
Thanks guys thats all very helpful. i took all the guards and stuff off the accumulators. still waiting on this mechanic to come with his nitrogen setup. If he doesnt come monday im just going to buy tht setup off ebay. i will definitely rebuild these myself if they dont hold the charge. typica cat guy telling me to buy new accumulators for 1200 a piece rather than just resealing them. thanks for saving me on that.
In conversations with Jake I recommended a seal kit, a replacement charging valve core (or indeed the complete charging valve), and the O-Ring for the charging valve that is not part of the accumulator seal kit. Even if only the valve core was replaced I would still remove the valve assembly and replace the O-Ring between it and the accumulator. That ought to cover every eventuality. Seal kit appears at around $170, complete charging valve (includes core) $60, O-Ring $1, charging valve core alone $12.
Where did you hook up the second gauge to see pilot pump oil going to the brake valve?
The inside accumulator had 0psi and the outside one had about 400psi. Charged them both to 800 and everything seems to be working fine now. I guess time will tell if they hold their charges
I'd suggest to take the pressures after maybe a month of operation. If the pressure either one has significantly decreased (more than 10-20psi) in that time I'd personally plan to re-seal them both.
We have trouble in the cold weather with accumulator piston seals leaking. The pistons are aluminum on the ones I’ve rebuilt and they shrink faster than the steel tube they’re in so if the seals aren’t like new they leak down. I’ve also noticed the aluminum piston will have a groove worn in them where the seals sit. If the groove is bad you will need to replace the piston. You are also supposed to put some oil on the nitrogen side to lube the seals as they slide.
That makes sense about the cold weather. Especially since this machine sits for almost all the winter.
With the machine dating from 2007 the piston seals being hardened with age and having taken a set is entirely possible. I'd imagine the accumulators have never been resealed before.
Hi we are facing similar problem , based on last thread we shall check brake accumulator today , can you confirm your problem was permanently resolved with this fix. We have so far changed - Pilot pump , Implement control solenoid , all 4 cartridges , but pilot pressure suddenly becomes zero. We have been struggling for months with this .
As far as I know re-sealing and charging the accumulators fixed the problem. Have you tried the "pumping the brake pedal" test as detailed in post #27 on Page 2 yet.?
Thanks for your quick response , we tried , but brake charging pressure is not exceeding beyond 800 PSI , guess problem with accumulator charging valve .