850K Code 3719.10 - DPF filling too quick

[clearprop]

I talked to the local JD service manager. He tells me the ECM calculates DPF level via 3 different ways and this code means of the 3 different calculations, 1 of them does not agree with the others.

This causes the machine to run a regen about every 4-5 hrs of operation.

I would assume one way is the DPF differential pressure sensor, don't know about the other 2. When I asked him about testing it he keeps wanting to just come plug the computer in $$$$.......I would like to troubleshoot wiring and voltages on my own prior to some service tech wanting to come play with his laptop.

I have a shop service manual but it has nothing in it about this code or about how to test the sensor.

By studying the wiring harness I can see it uses a supply voltage of 5V, a return (GND) and a signal. Any idea what voltage the signal should read engine off and engine running with clean DPF, and with dirty DPF?

If I at least test the sensors out I might stand a chance...?

 

[funwithfuel]

Its emissions related, they dont want you screwing with it. That said, I had a similar problem in a haul truck. As soon as it came out of regen, it wanted to go back at it. It turned out to be a damaged nipple of the psi diff sensor. The problem is you're trying to convert a complex measurement to a voltage where those differences would be recorded as /100ths of a volt against a known chart. That's where the computer is irreplaceable. If you want to do real , yet simple troubleshooting. Remove the piping and sensors from DPF. Check it all over for cracks or soot. Check the silicone joints for burns. Make sure the sensor nipples aren't cracked. Let it thaw out(if frozen) and see if any moisture comes from the nipples. Lastly, verify the tubes are clean inside. No restrictions. Good luck

 

[clearprop]

Its emissions related, they dont want you screwing with it. That said, I had a similar problem in a haul truck. As soon as it came out of regen, it wanted to go back at it. It turned out to be a damaged nipple of the psi diff sensor. The problem is you're trying to convert a complex measurement to a voltage where those differences would be recorded as /100ths of a volt against a known chart. That's where the computer is irreplaceable. If you want to do real , yet simple troubleshooting. Remove the piping and sensors from DPF. Check it all over for cracks or soot. Check the silicone joints for burns. Make sure the sensor nipples aren't cracked. Let it thaw out(if frozen) and see if any moisture comes from the nipples. Lastly, verify the tubes are clean inside. No restrictions. Good luck

Thanks.

I will dig into it. Also I will trace the wires. Was hoping that prior to going back onsite I could per chance find the test procedure for the sensor. something like 0 psi = x volts 1 psi = x volts 2 psi = x volts ......etc. I see from the wiring shop manual that it is called a 5 psi sensor to I would guess that is the range of the sensor, however, I would guess the operating range in this application to be quite a bit less.

 

[mg2361]

They want to see time based, fuel based and differential pressure based models to help determine what direction to go in. No there is no set spec for readings out of the differential pressure sensor. Also you need the engine operation and test manual for troubleshooting (CTM104719 for iT4, CTM120019 for FT4). For example if the pressure based and fuel based are high and time based is not then there is something else causing the DPF to plug like turbo leakage, injector not firing quite right, coolant from an EGR cooler, bad rings, just to name a few. Also there are several other sensors used for that calculation that if they are showing false readings that are still not far enough out to prompt a code then the whole calculation is off. If you have JDLink the dealer can look at those readings from the shop without coming out. Also with 3719 codes the dealer may have to come out to clear them. If you have a 3719.00 code in memory that is a latched code and the dealer needs to clear it.

 

[clearprop]

Been too wet to run lately. Got back to job site and tore into it a little.

Traced all wiring and checked out good from ECM connector to DPF pressure sensor.

Noticed little stem of grass in DPF sensor port when removing.

Went ahead and built up a 5 volt voltage generator and tested the sensor. Shows a 0.71 volt output at Ambien pressure on both ports and then up to about 4.7 volts at around 5 psi so appears about what I would expect without technical data.
Investigated the hoses between the sensor and DPF and found the blockage in the picture. Hope the gremilin has been found but who knows.