HFservicesNC
Active Member
I bought a 700k dozer back in 2019 used that had dropped a valve. I had my mechanic at the time rebuild the engine and get the machine operational. After rebuilding the machine and getting it going it had a camshaft sensor error that we believed to be in the wiring. We ran it like that for a while until here recently It started to derate the machine. You could clear the code and it would run like it was supposed to for 10 to 15 minutes and then derate again. I replaced a cam position sensor which did not fix the problem. I got tired of dealing with it so called our local John Deere construction equipment dealer and had them come out to look at it. The John Deere service tech replaced the cam position sensor, Ran wires directly from the cam sensor to the ECM and tried a Donor ECM with no change. They then recommended that I bring the machine in for them to tear the front half of the engine apart since they believed it was a problem with the camshaft gear that the sensor reads. Today my mechanic and I pulled the fuel pump that gives access to the camshaft gear and didn’t see any problems. I then went ahead and replaced the crank sensor for good measure since the dealer didn’t Mess with the crank sensor. I checked all wiring and connections from the crank and cam sensors to the ECM and everything checks out good. I cleared all the codes and ran it with the same result. ECU code 636.10 - cam sensor pattern error. I logged in to the troubleshooting menu and observed the cam and crank rpm. The crank rpm would hover around 900 rpm at idol and the cam would do about the same but a lot more erratic. After watching it for a couple minutes I noticed that the cam rpm would randomly spike up to 3000 RPM and then drop back down to 900 and then spike back up to 3000. I am thinking the dealer may have been wrong about the ECM and that is actually the problem but they still want me to Bering it in for them to tear the front gear cover off. Anyone have any suggestions or thoughts?