John Deere 624K Wheel Loader 1DW624KZVEF663141 6.8L Powertech 6068 Level 33 Machine is very hard to start is cold temps. When I was called out to the machine it was running very rough. Code 157.16 Fuel rail pressure high Cylinder performance test was showing cylinders 4,5,6 more then 10% deviation from 1,2,3 Brought back to shop, machine seems to consume a lot of fuel and struggles under load. Without a load actual fuel rail pressure stays in line with desired until reaching higher RPM where around 20k desired becomes about 24k actual and sets code. Pressure stays over desired until idling for a moment. Set machine engine off for 10min, fuel rail pressure reading was less then 145psi with scan tool Pressure relief valve and solenoid was made new. Disconnected return line from air to fuel cooler and routed into a 5gal pale to remove any downstream restriction. Return was measured at MAYBE 25ml/min at 1800rpm. Again performed cylinder performance and all cylinders within 2% of each other But sustaining higher RPM brings back 157.16 code consistently I pulled the injectors and sent them to a fuel injection shop too be tested. Did it make sense too do this? Any other recommendations for diagnosing this issue? First time running into a rail pressure high situation, normally its too LOW not too HIGH!!
Is the rail relief lifting at any time? Is this one of those ones that has the shorty pressure control valve solenoid that there seems to have been an update on?
It could still be the SCV. Are you using Service Advisor, or another diagnostic software?
I cannot say for sure, however the new pressure control valve was different on the valve end, there was a straight boss instead of a taper, I will post a pic momentarily I am using Jaltest our EDL is occupied in another location for a time. Is there a DTAC I am missing for the SCV or is there a check I can perform with SA or mechanically?
The original is the left, replacement right, difference in the top
This pump seems to have two "Pressure Control Valve" instead of a suction control valve
Sorry, you are correct, I assumed a 6068 with the SCV. Check your messages.
Thanks for the messages. I did follow through on the high pressure fuel system diag before hand. John Deere is very hit or miss with their diag's. My plan is to wait for the injector shop to get back to me on the injectors and if they are good I'll be replacing the injection pump. I couldn't find the 'pressure control valve' listed in any of the fuel system parts break downs so I just called my dealer and asked him if he could give me a break down of the pump. Apparently JD lists the valves as non-serviceable and the entire pump assembly needs replaced for a faulty valve. I asked him if he had any issues with these pumps and he asked me how many hours the machine had which is about 6800hr and he said we got more out of it then they normally see. 6000hr being the average. Anyways he said that the fuel bypasses the pressure control valve and enters unmetered to the rail causing high pressure. Thinking about it again it does explain why I was having issues with cylinder performance on cylinders 4-5-6 at the peak of its temper tantrum. 2 chambers, 1 for 1-2-3 and 2 for 4-5-6 and my issue is with 2 seemingly. Anyways thanks for the help, hopefully once all is solved with a new pump or possibly injectors I will update the thread. It's only a matter of time until someone like me is looking for clues.
You're not kidding about that .
Well the injector shop told me the injectors tested good so I decided to replace the fuel injection pump, the common rail pressure relief valve & solenoid, and common rail pressure sensor. The tactor isn't throwing and rail pressure high codes anymore, but the engine lacked power and stumbled under load at low RPM. I did a cylinder contribution test and the same cylinders 4-5-6 showed 13% low, did a injector kill test and 0 change when killing 4, 5, or 6. Ran another relative compression test and nothing is standing out with compression. Put 6 new injectors in with a new injector harness and no change. Still slow to build RPM, still seems like a miss, still no change when killing injectors 4, 5, or 6. I am at a loss for what could be causing this injector issue on 4, 5, and 6... I guess it could be a MOSFET or driver issue in the ECM but after talking to Deere he said he hasn't seen any issues with these modules only pump and injector failures. Something is going over my head...
No codes at all? For anything? Stored or not? All the grounds on the machine clean and tight? Especially ECU related grounds. That is still a possibility. I have seen driver issues on the 650 dozer and 310SK backhoe ECU's with no codes. It would have to be the common voltage supply wire. All the injector grounds are separate. You could check the common voltage wire to the injectors if you have a scope. That is a peak and hold injection system. It peaks at 90 volts to open the injectors, then drops to approximately 12 volts to hold them open for whatever duration the ECU commands. I see there is a new payload available for your ECU and VCU. Might be worth having them updated. Reaching here. Is your air intake system sound. No blown hoses going into or out of the charge air cooler and to the engine?
the only code coming up now is 521379.17 Hydraulic tank pressure low. I’m not sure yet what is causing this yet maybe a tank air leak or sensor. I don’t remember it being there before but I never open the hydraulic system or went near that sensor. The tank pressure holds at 0 all the time. I’ll go over the grounds again today. I have a cheap scope that has been giving me issues I don’t think the attenuators is working correctly. I have been considering getting a picoscope. I was hoping to avoid having Deere come out and update the ECM. As far as the intake system goes everything is intact and in good condition.
I fixed the hydraulic tank pressure code with cleaning up the connector at the tank sensor. Seems to be the reason it would idle at 1200rpm sometimes. Getting .5psi at the tank now. Looking at the wiring schematic I only saw one ground for the ECM that was below the common rail on the engine. I cleaned it up but it was in pretty good shape. I poked around on the injection harness at the rocker box. My scope wasn't much use it's more hobby grade then professional... I used it with automotive but never needed it for the GDI engines. I think I'm going to have to upgrade my scope too really get into these common rail systems now that I'm working on the diesel side of things. I'm looking at a Picoscope 4225A diesel kit, and I'm also looking at a sensor that can handle actually plumbing into the 30k or so psi of a common rail, as well as some inductive sensors for actually picking up the vibrations of the injector supply pipes individually, and some glow plug adaptors for compression testing. I did just take a basic frequency test with my DMM on the supply side of the EFI for injectors 1-2-3 and compared it to my problematic 4-5-6 side. The frequency on 4-5-6 was about a 1/4 of what 1-2-3 was. I passed this info along to my service manager and just explained I'm at the limit of what I can do with my current tooling and that replacing the ECM was my best diagnosis at this point having load tested the circuits and replacing the injectors and injector harness as well as the relative compression testing and other clues. I told him he would either have to wait for me to get a picoscope or have a Deere tech come and look at it to have any further confidence in replacing the ECM as the solution. We quoted a ECM from Deere with programming and it was very fairly priced. So he pulled the trigger on an ECM replacement. They are going to bench program it for a very fair price. Our local Deere dealership and tech is insanely knowledgeable and helpful. My service manager knows that I am relatively inexperienced with common rail fuel systems on diesels so I'm lucky to have understanding that it's a learning process right now. We have a whole fleet of these loaders and this is currently our only level 33 T4F machine, but we are in the process of upgrading them all so it's going to be a education that's worth it in the long run. Should be replacing the ECM mid-next week and update then.
I think you did a real thorough job of troubleshooting. Want a job? Definitely let us know the end result. Nice. I just use the PICO 2204A. Gets me by. With that scope and all the adapters, leads, amp clamps, attenuators, etc, I don't think I spent more than $500 for everything. Not as nice as the 4225, but when I bought mine 6-7 years ago, I didn't want to spend that much money, not at my age.
Problem solved! I removed the original ECM out and took it down to the dealer, they loaded the new payload on the replacement and then copied all the parameters over. Plugged the new ECM in, turn the battery disconnect on, ignition on engine off for about 3 min and the a communication fault changed to inactive. Cycled the ignition and started it. Runs like a dream. No codes, no rough running, plenty of power, all fuel pressure are good. I wish there wasn't a core charge on the bad ECM, I wanted to open in up and see what kind of mosfet they using to drive the injection circuit. I've had good results repairing smd components for other repairs. The hydraulic tank pressure low error came back, I traced the hose back from the tank to the engine charge air pipe behind the cooling pack bulkhead and found a corroded check valve. Cleaned it out and got it working again, chucked it in the ultrasonic cleaner for the night. Appreciate all the help, I learned a massive amount from this diag that will undoubtably help me in future diagnosing.
Thanks so much for putting it all up here. I can't fathom most of the acronyms and that won't matter to a trained technician. The problems and solution are all here, that is what matters.
Great job, Bullitt! And thanks for posting the fix.
Good afternoon, I have a 644k with 521379.4 hydraulic air tank sensor shorted to ground. stored code. Where is the pressure sensor located? For the lift of me can’t find any diagrams anywhere. I work for a chemical plant, we Are contracted to do pms on equipment but have since started doing minor repairs to equipment. Any help is appreciated thanks.
Welcome to HEF Notsamuel ! The hydraulic tank pressure sensor is located on top of the hydraulic reservoir between the fill and filter on the left side of the machine under the step. If you need further assistance, I suggest you start your own thread and post the machine serial number since there are 11 variations of that machine.
Thanks for the welcome! Newish to loaders, having a lot of issues with upfitter parts as well so I have my hands full with no diagrams! I will post a new thread, thanks!