Agriculture and Farm Equipment
Agriculture and Farm Equipment Repair Questions? Ask a Mechanic.
Good afternoon my name is ***** ***** ill be your tech today. first I need to know what controller is giving that code
I have 10 years of John Deere experience. that tractor has several different controllers in it and before I spent my time looking up the info I wanted to be sure we were all talking about the same thing. I will opt out and let another expert pick this up
ok, I will start looking up the info and diagnostics
I know you said you switched a bunch of high pressure rail parts from one tractor to the other. the reason that it ma not have shown any issues is because of the difference in ECU software versions. so assuming that all the respective parts are back on there respective tractors lets start with the relieve valve. the code indicated that there is an issue with pressure in the common rail system. the ECM is looking at the actual pressure and comparing it to the target desired pressure. assuming that you know which valve is the relieve valve, remove the line from the top of the relief valve and start the tractor. run the engine slowly up to high rpm and watch to see if there is fuel coming from the relieve valve. report back with your findings and we can run from there
I believe in diagnosing the problem and not throwing parts at an issue. did you do the test?
run the engine slowly up to high rpm and watch to see if there is fuel coming from the relieve valve
no it does not have to run long
is that code currently active now?
it would be worth testing the pressure sensor. between pin 1 and pin 3 you should have 1K-3K ohms
between pin 1 and pin 2 you should have 8K to 16.4K ohms
test done engine off key off sensor unplugged
if you enter into ECU address 038 that will display the rail pressure that the sensor is seeing. key on engine off that value should be zero. can you enter into the ECM address?
I suspect that the suction control valve has failed and is causing the relieve valve to unload fuel pressure. the basis of this code is that the desired and actual pressures don't match. with out connecting this tractor to service advisor you will never know what exactly the pressures are. when we diagnose this issue here we have the tractor on the DYNO and the laptop connected to watch pressures. I would do the sensor test that I described and if you don't find an issue there you will need Deere to come out and connect with the laptop to get those readings. remember, if the suction control valve is found to be faulty the relieve valve should be replaced as well
sounds like you have pin pointed the situation where this code trips. you could duplicate those conditions and recheck the relief valve when you have met that condition
we are only concerned with fuel rail pressure actual and desired. the code is saying that your 725PSI off (high or low)
SA can graph the 2 measurements so that you can see what is actually going on.
that is also assuming that the pressure sensor is working properly. preform pressure sensor test first. while connected to SA run the tractor in all conditions and watch to see if you find a condition that makes the 2 reading separate that 725 psi
I don't really need the graph. your a smart man and I trust that what you see you will report back accurately. just watch the reading. if indeed these reading do separate then it proves that the suction control valve has failed
and I also remind you that we don't know what the programming is in the ECM of these tractors. different software versions have different ideas as to where it may want to see pressure.
I wouldn't change the relief valve until you know why the relief valve failed. they are not designed to relief very many times. if you install a new valve and there is still an issue you will ruin the valve
what model was the tractor you swapped parts with?
another test that can be done is checking for air in the low pressure fuel system. disconnect the return line and install a clear plastic hose. run the tractor and look for air bubbles. that would indicate an air leak
the same can be done on the pressure side of the system going into the pump. install a clear plastic line between the pump and filter. run the tractor and check for air bubbles
cylinder cut out and injectors..... unless you have codes for them then there is no reason to do anything with them. this issue per code is strictly common rail related.
not sure why RPM would effect it. that's is why having it on a dyno for testing makes the job a bit easier
none of that really matters when it comes to the correct diagnosis for the code. the pressure is either there or its not
no I cant do that. in the US the software is held on a dealer level. I now run an independent repair shop
unfortunately there isn't any info there that helps. we know the engine fires correctly. we need to see desired and actual fuel pressure when this issue occurs.
ok. can you get a reading on desired and actual fuel PSI?
have you done a desired to actual graph when the issue has occurred? if so what did you find??
did you get this resolved?
i really wish you would do the desired and actually tests with the laptop
im not going to guess. this needs laptop diagnostics. Im not the type of tech that throws parts at a problem until there fixed