Dealing with an issue when the engine would abort parked regen and instruct to check active codes. 650K E273176 Active codes: 27 3 EGR position open or short 3251 4 DPF pressure short to ground 1569 31 engine derate active 3719 16 Filter soot level very high 111 18 Engine coolant level low After repairing rodent harness damage at the EGR connector and finding a harness plug connector loose behind the fan, the EGR and coolant level codes went inactive. The other three remain active. So I am trying to run down the 3251 4. Can't find any short to ground at the DPF pressure differential sensor or the exhaust temp sensor which share power supply. The DPF sensor shares return with intake, charge air and EGR to sensors. Checked the sensors for ground and ohms . The intake and charge air sensors both ohm about the same , but EGR temp sensor has double the ohms of the other two. It looks the same as the other two but has a copper washer instead of oring seal and the plugs won't interchange. So I decide to try the parked Regen ant this time and it completed it!! But the 3251 4 code is still active but the only active code. The service book yellow is NOT on anymore. So does anybody have any Idea if I need to keep trying to resolve this code or call it good? I can't find any short in the circuit and machine functions properly. Just that is worrying me there is still an issue that may affect the auto regens in the future. Thanks
It will need to be fixed. DPF pressure readings are vital to determining the frequency of regeneration's. Errors with that reading will most likely result in frequent regen's. Do have software to plug in? Did you backprobe the DPF connector and check the 5 V reference voltage, return voltage and signal voltages? I'm out of time this morning but will think on it and have some more questions later.
I do not have service advisor but have aftermarket that will communicate and show live data. Have not hook hooked into it. Made it this far with the machine monitor and wiring schematic. Yes I checked the five volt referece . I have also replaced the pressure sensor. Late yesterday I did find the DPF outlet pressure tube loose . I tightened it up , but code remained.
So 650 K left today. Seems to be operating fine . Before it left I was thinking that the DPF temp sensor(s) could cause the short because they share a common power supply. But the DPF temp is a module that when unplugged gives a lose of CAN code. There are two wires leaving the temp module to each of the three temp probes. The wires coming out the module are molded into the module so I could not back prop . Was going to remove the sensor probes to do a visual inspection but the float showed up. And somewhere along the way I removed the pressure tubes, differential sensor and its manifold to check for blockage.
Your issue is with the signal wire circuitry, not the reference voltage circuitry. If you lost reference voltage then there would be codes for the exhaust temperature and the coolant pressure sensor (if used) since they share the 5 V reference circuit. I guess we'll revisit this if your issues return.