Can you just connect a new ECU to the John Deere 7830 or does something else have to be done to make it work? Today I was cultivating in the field with our 7830 and the engine fan speed was very erratic and ran very fast most of the time, but I never had a code for that and it was not running hot so I just kept going. Then I got the code ECU2795.07 Variable geometry turbo control error, followed by the code ECU1569.31 Decreased engine power. So I stopped and checked all the codes and there was also a fuel rail pressure control error ECU 1347.07. Surely the turbo and the fuel system had no problems at the same time. The common among all this is the ECU. What are your thoughts guys? I have purchased a Reman ECU from the local Deere dealer and it costs $ 1630 with $ 200 core. But they have told me that if I connect it I cannot return it. Thanks for the help in advance.
A reman or new ECU will not be programmed. Your dealer must program it for your tractor (based on the serial number). I suggest you clear all the codes and check if any are still active. If not, run the tractor again to see which ones kick in and diagnose from there.
A used ECU will work as well but again needs to be reprogrammed for your vehicle. Even if it is an identical tractor, it will throw up codes that do not match the VIN due to an incorrect serial number.
Check the viscous fan clutch at the front of the engine. I have replaced them in 7×20 and 7×30 for similar problems. There should be a fair amount of resistance turning the fan with the engine off. When the tractor is turned off after it has been running, the fan should not rotate freely to a stop.