I have a Hitachi ex200-3 excavator with thumb. It is my first machine and I’m not a professional. I have several issues that all started this winter. 1—When starting the machine this winter and since then the throttle started pulsing up and down and the power buttons have no effect. I have to shut it off and restart it until it revs more normally sometimes many times until it suddenly stays at more appropriate rpms. However when it does finally stay at a consistent rpm the rpms are either on the fast or slow range. For instance if I finally get it to start without pulsing the power level might be low and pressing p brings rpms up but not to a very high level as it used to be. At other starts the rpm level is very high like in p mode. The only consistent thing is the usually many starts to get an even rpm whether that be high or low 2—to even be able to start the machine I have to jump the + of the inside battery to the starter side terminal of what I think is the starting relay which was just replaced. It’s the only way the top red light on the starter panel comes on and allows me to start the machine. 3— The inside battery, the one connected to the above mentioned relay keeps dying and yet it’s the newer of the batteries. Any advice on troubleshooting would be appreciated. I’m in Far Northern California on the salmon river and it’s very hard to find a trustworthy mechanic to come out here. Thanks in advance for any help Howard
Sounds like you have some electrical issues.... A few things about the starting system: these machines use the alternator as the return path for the starter solenoid... so if it is running it won't let the starter engage - however if there is something wrong with that part of the alternator it won't start with the key switch. The reving thing I'm not sure... could be you have an issue with the ECU or maybe it's related to the alternator problem??? what voltage is it charging at when running? if you're getting high voltages or something it can harm the computer... is the 'heartbeat' led light flashing on the ECU?( behind seat back left) There is a schematic on here somewhere if you search for a thread on hitachi ex120 problems( the file is for ex200 but they are basically the same) The batteries dying could be related to the alternator too.... disconnect the alternator next time you gonna park it for a while.. there is a disconnect solenoid (big round can looking thing) right after the batteries it might be staying on.... it is supposed to stay on for a little bit after shutdown to protect the computer but maybe someone rigged it up different or it has issues???