So one of my customers has a 279d that suddenly lost bucket lower function. Initially when I went to investigate the issue the ambient temperature was below 25 degrees f. The code exhibited was a low current code on the bucket lower solenoid. The machine was moved back to the customers shop and left indoors. I went to check it out at their shop and miraculously it began working again. Long story short I quickly realized that the issue had to be related to ambient temperature. I discovered a few ground connections and replaced the battery as well as repair or replace any questionable grounds and I replaced the bucket lower solenoid even though I couldn't verify the issue. The machine was left outdoors again and again did not work. We left it inside again and it was again working perfectly fine. I decided to pull the ECM and throw it in their freezer. Once I installed the cold ECM into the warm machine the problem again showed its face. There were other codes for low current and from what I could tell they all traced to the same 300ma pin on the ECM. I cannot find any information on this being a known problem, anyone here seen this before with a cat ECM? Initially I thought it had to be related to the grounds and the ambient temperature made the issue present itself, but now I isolated that the issue is only when the ECM itself is cold.... Customer wants more proof... Any thoughts?
Please post a machine Serial Number and the exact Diagnostic Code you saw. Troubleshooting procedure and an electrical schematic will follow. IMHO a dodgy ECM is unlikely but possible. My first suggestion would be to measure the pin drag on relevant terminal(s) of the ECM connector related to the Code you saw, but without knowing which wire you are referring to it's hard to comment further.
CAT0279DPGTL00914 is the complete serial number. The code in question when presented (again only once machine has sat out in the cold) is 355-5 bucket lower solenoid current below normal. My initial process was mildly simple as there were multiple machines down for this customer ahead of a looming snowstorm. Initially I realized that there was also a code for fuel pump relay current below normal (1627-5). The customer wanted a fast answer and was willing to purchase a solenoid. I did a voltage drop test on the ground cable in the engine bay as well as the ground strap on the back of the cab and I was not happy with the results (slightly higher than .02volts) so I replaced them both along with the battery (I had a new one on my truck) to rule out the simple things. I noticed a long list of seemingly unrelated inactive codes. The customer sent the machine out, it worked fine fresh out of the shop until it went on a trailer to the job site. I was called to come back but again it was indoors and the problem seemingly vanished. From there I thought I could potentially isolate the problem by removing the ECM and placing it inside the freezer. I left the ECM in the freezer until it was very cold to the touch. The rest of the machine remained in the heated bay inside their shop. I reinstalled the ECM and the problem immediately was present. After about 1 hour the problem was gone again. If the machine sits outdoors for 3 days it will not work for 3 days, if it sits inside the shop it will work fine for as long as it sits in the warm temperature. The machine worked fine all summer as well. I did suspect that a positive cable potentially was an issue and I did also do a voltage drop test on it but now that it seems to be when the physical ECM itself is cold... I'm very suspicious that it may be the issue itself. I understand that is very unusual... Which is exactly why I am here lol. I will attach some screenshots of the cable in question(via diagram) a long with the circuit on question. (I have access to cat et and a variety of factory information).
OK, so you already have all the info I was thinking to send to you. Based on the FMI05 current lower than normal for a kickoff I would suspect a connection somewhere, and maybe not at either the ECM end or the solenoid end. I see CONN 5 in the rear cab wiring alongside the ECM that also might bear some close investigation. My first suggestion is to check the pin drag on Pin 33 of ECM connector J2, since the other Pin of the circuit (J1 Pin 14) is common to all four of the implement function solenoids. I would also suggest to open up CONN 5 and look closely at both halves of Pin 4. Compare the drag on that pin with others around it. Is it looser than them or about the same.?
J1-pin14 is common to a few Implement function solenoids as you stated. Took me a few minutes to follow the wires from one schematic page to another, but you were right and it was as stated. Found that 103-MM1RD-4 cable that carries all the current on the schematic. Question? How do you know on the schematic if all the cables at Battery Positive are lugs for going on a 3/8 stud versus the Lead Post looks like a thumb connection. You must have a good computer set up no doubt. Reason I ask is that those lead soldered type post set ups are very prone to one leg of connection being compromised. Simon C
Ok sorry for taking so long to get back. Pin drag test was more or less inconclusive. I double checked every circuit and connection I could find. There was also a perpetual fuel pump relay current too low code as well as an event for cold engine. Got a new ECM from cat and had them configure it on site.... Problem solved. I spoke to two local cat mobile techs as well as a guy who I know who used to work at cat and all of them felt the same as me... Very strange, never heard of a failure like this and hesitant to say it's the ecm... But hey, there's always something new lol. Thank you for all the help folks!
Thanks for coming back and updating the thread. Sorry the fix was so expensive. The pain of having to buy a new ECM never goes away....
The "cold engine" E60032 Event is fixable (or at least the message on the screen changes) with an updated engine software IIRC. Effectively it's the software doing what it's supposed to do by limiting the maximum permitted engine RPM until the coolant temperature reaches a certain value. My mind is a bit hazy on the details.