[kversh]

I am working on a 9770sts combine and am having problems. The codes started last fall and have only continued to get worse. The codes are ECU 3510.03, 641.12 and 100.04. No real performance issues have been noticed but the turbo actuator is not working correctly causing the derate code to come active. All software has been updated I have tried a new turbo actuator. The original actuator responds to a learn calibration through the computer. I performed a harness diagnostic test and get a code for egr valve which has checked out ok. The voltage at the oil pressure sensor is 4.2-4.3 volts. I am leaning towards an ECU but I am not sure and pulling my hair out!! Sorry for the length of the post and thanks for any help- Kevin

 

[chicken wing]

So the codes are low sensor voltage. Oil pressure sensor and acuator not communicating. I think I would be checking can voltage and also very closely checking every pin of each connector between engine and ecu.

 

[neilglenvar1]

I would check the harness just before the plug where it plugs into the ecu for rubbed or broken wires then check the harness between the ecu and the turbo and oil pressure sensor

 

[lanwickum]

ECUs fail, not often. They are repeatable every time I have seen them fail. I have replaced 4 in 10 years of being a mechanic. Pain to diagnose. Often the best way to diagnose is to swap with another machine. See if the problems fallow. Not always possible. If both ends of the harness read the same and is in specs. Well.... But, it is a CAN BUS system. Makes it even better to diagnose. Terminators failing cause weird problems. Good luck, I never worked on CAN BUS enough to know like I should.

 

[kversh]

I think I found the problem, fuel pump in the top of the fuel filter. Heard from someone there was a pip on these pumps at one time. I unplugged the pump and with the key on all my codes went away and the turbo actuator cycled. Installed a new pump yesterday and so far codes are all gone. Thanks everyone for your help- Kevin

 

[chicken wing]

Good job. I changed lots of those pumps but not for that reason. Good to know.