Well I continue to work on this machine. Right now switching the MFWD switch to 2wd causes the machine to turn on the parking brake. If I stay in MFWD all is well and machine operates properly. I do notice the parking brake/stop light turning on momentarily when I change direction in 2wd on the F-N-R lever, but its only on for a second. I did check the resistance at the MFWD solenoid and it is about 8 ohms. I also verified that I have voltage at the electrical connector when I switch to 2wd. I'm wondering if a drop in hydraulic pressure for some reason when going to 2wd mode is causing the parking brake to be applied? If I switch the machine back to MFWD, the parking brake goes back off and all is well again.
I removed, cleaned and tested the solenoid. It seemed to work fine. As you can see below I did find some dirt or other matter on the screen. I cleaned it best I could and reinstalled it. No change in operation however.
This probably didn't any type of helpful answer but when I got my 310d it had the parking brake disabled. Guy said it's electric and acts stupid, that I can re enable it if I want but it's a pain in the butt when it engages somewhere inconvenient for no good reason. He said to put a foot down if I don't want it to roll away. I haven't reconnected it. Good luck.
Thanks. I should also mention that the tractor stays in mfwd mode when switching to 2wd in addition to turning on parking brake. I live on top of ridge so I would rather not disable the parking brake.
I believe the test port for the MFWD on this tractor is next to the solenoid. I'm thinking next I need to see if I have hydraulic pressure there when 2wd is activated?
I don't know this equipment but, I do know electrical and electronics. Check for good grounds and clean connectors. Use an ohm meter between where the solenoid is and the main ground. Should be under 10 ohms. 1 to 4 is what I expect. Also make sure you don't have a pinched wiring harness somewhere. This sounds like an intermittent electrical issue to me. If in doubt you can add in an extra ground strap from the pump to the chassis
I have done this. I have also bench tested the solenoid in question and it works properly. At this point I'm suspecting a sliding collar in the MFWD control section of the transmission. A spring keeps the transmission in MFWD by default. When the solenoid is activated it opens a passage way which adds hydraulic pressure to sliding collar which pushes against the previously mentioned spring and thereby changing the transmission to 2wd. Maybe my sliding collar is no longer sliding?