Our 2015 John Deere 290G hydraulic thumb is having erratic behavior. At times is will not activate, but once activated it it may continue in the one direction, open or close without stopping. You can keep clicking the button and it may stop momentarily and then continue the other direction. At times it will not respond at all. When this happens, I could bleed a line on the cylinder and then it would open or close with the button on Joystick but really does not respond well. Where would you guys start testing this issue. Thanks in advance.
This is 95% electrical. Start with that joystick switch, it's the most common failure point for erratic aux behavior on Deere machines. Self-actuating in one direction because of solenoid valve stuck energized or shorted wiring continuously powering valve Won't respond, then works after bleeding because of air in system OR electrical signal intermittently failing (bleeding forces manual reset) Solenoid valve coil failure : Aux valve solenoids sticking mechanically or electrically shorted. Test it by disconnecting solenoid connectors, if thumb stops self-actuating, solenoid/wiring issue confirmed Controller/CAN bus issue : ECM sending bad signals to aux circuit (less common but possible) Don't chase hydraulic issues, replace switch or solenoid valve, depending on test results. Budget $100-300 for parts.
Thanks for the info, makes sense. I'll try testing those things.
I was thinking electrical or a bad solenoid... thanks to your advice, I traced the wires from the joy stick and unplugged them behind the seat before they enter the ECM. I could jump either wire and get the desired open or close of the hydraulic thumb. It appears the joy stick is faulty and sending a continuous hot (open) signal. I verified this with a voltage meter. I've ordered a new grip and this should solve the issue.
Happy to know that I could help! Keep on updating status.