We have a 2000 544H John Deere loader that the hydraulics are not working on it. acts like it does with the hydraulics are turned off by the pilot enable switch. I have 26-27 volts at the pilot enable coil on the pressure reducing valve, and it goes on and off with the switch in the cab that turns the hydraulics on and off. the machine will move and steer but no hydraulics. checked fuses, was blowing the return to dig and return to carry fuse, I think I have that fixed, pilot enable fuse is good, coil on the valve shows continuity and not shorted to ground. was going to swap two coils and see if there is any change, of course they are not coming off. Do you think I'm on the right track? Any suggestions?
The pilot coil needs power and ground to activate. If the coil will not come off there could be enough corrosion between the coil and the stem to keep the valve from opening . The pressure reducing valve could broken and dumping pilot oil. Sometimes wiggling the adjustment on the pressure reducing valve will bring the pilot pressure back.
Welcome to HEF Homer ! Does your pilot controller feel limp? There is usually a noticeable difference in the pilot controller feel with the enable switch on or off. Sometimes if you just leave your hand resting on the pilot controller when turning the enable switch on and off you can feel it pulse as the enable switch is cycled. Either way, if you have voltage to the enable solenoid and a good ground at the solenoid then you might have a stuck spool inside the enable solenoid stem. The only way to be sure is to check pilot pressure. That's where I would start. If you have pilot pressure then you have other issues.
Thanks,Guys. It did it a couple of times while loading over the course of a week and quit all togother. Now if I can get that dog gone coil off... I don't have the gauges to check as most of our work is on Peterbilts. Can they be bought online or at O'reillys?
I don't think that you're gonna find 24v coils st O'Reilly's. Do you have hydraulic test gauges?
I was referring to the gauges. I don't have any ,seen some on amazon that have several adapters, supposed to work on komatsu and Cat excavators, hate to buy them until I know what adapters I need, open to suggestions. I did get the coil off with the Lord's help as it was pretty rusty on the outside with some on the inside. polished the valve and inside of the coil. Checked operation, still no hydraulics except for the steering. Swapped coils, same result. The 2 coils ohmed out the same. Cleaned ground cable on starter, same result. Found the braided ground cable from chassis to the cab about rotted in two, replacing that now, will advise. I appreciate all the help
no change with the new ground cable from chassis to cab
If your comfortable with pressure testing then acquire a gauge (5000 psi, which can be used for further testing if required), diagnostic quick couplers and a long whip hose to connect to the diagnostic coupler on the pressure reducing valve. You need to check pilot pressure (600-650 psi). Post results.
did you ever figure this issue out? I am having similar problems.