Working on a Hitachi ZX85USB 3 that won't rev up. Throttle cable is good and it revs up when you pull it. Stepper motor and gear box are also good. Does anyone have a electrical schematic or manual that explains how the system works? S/N HCM1P700H00082365
Maybe Diesel Dave or mg2361 will have. I would send one if I had. Simon C
Does the monitor in your machine look like the one below? If so, did you go into the service menu and watch the EC Dial Angle to see if it changes with the dial operation? Do you know how to get into the service menu? Check your messages.
Yes the display does look like that. I'll see what I can find out. Thank-you for the attachments!
I was looking though the wiring diagram and it looks like the engine ECM only controls the throttle system. There is a learn switch on the diagram. What is that for? Not sure how to test the four wires to the stepper motor. The motor and position sensor are ok. ( Yes we loaded the parts canon and fired it. ) The old one would just set there and kind of viberate when you move the dial in the cab. The gear box was ok. so we though the motor was messed up. It is getting something through the harness it just must not be the right thing. The four wires to the motor would be power, ground, and then the other two would they have power to one to turn one way and than power to the other to turn the other way?
After EC motor replacement, an engine learn needs to be done. 1. Key off. 2. Move the learning switch to ON, aligning with the "E" on the guard. 3. Turn the key switch ON, wait 5 seconds. 4. Turn key switch OFF, wait 5 seconds. 5. Move the learning switch to OFF. I don't remember if the "D" series is a 3 position switch or a 2 position switch, but off would be the center position on a 3 position switch. 6. Check the engine speeds to see if they are correct. Check your messages for the EC motor voltage checks. I want to add, DO NOT unplug/plug the EC motor connector with the key on, or you will be buying a controller.
I did the voltage checks and they seemed to be ok. I did the engine learn and checked the continuity of the wires from the motor to the controller on the back of the cab. I did not have a good way to load test them right then. Than found the motor was working so I put it together and it worked good for a couple of weeks. Costumer said now it started to mess up. Sometimes wouldn't idle down sometimes won't rev up, and now it only stays at idle. The screen has a black circle in the middle of it to like it is a spot that is died. Not sure if the screen has anything to do with the throttle function. I want to get a repair manual download for it but I am having trouble finding the right one. Is it the same as a John Deere 85D? It has an Izuzu engine. Would the John Deere be a Yanmar? Maybe the throttle is the same regardless of the engine it uses.
Deere 85D has the same Isuzu engine as well. That being said the throttle /components are the same but I wouldn’t guarantee the electrical schematics match the Deere and Hitachi. The ZX85USB-3 Hitachi manuals are , Troubleshooting is # TT1P7E00 or TT1P7-E-00 . Operating Principal is # TO1P7E00 or TO1P7-E-00 . Workshop is # W1P7E00 or W1P7-E-00 .
Can you tell me what each manual contains? Which would have the wiring diagrams? Will any of them cover the engine?
Also search for ZX85USB LC -3. Some manuals sites have it listed that way only.
Troubleshooting has system test procedures and specs. The wiring diagrams will be in troubleshooting manual. Operating Principal , self explanatory (has no test procedures). The workshop manual will cover major components R&I and repair. It will also have a basic Isuzu 4LE2XYSA01 engine manual. It will have little engine emissions info/ troubleshooting.
Did you go into service menu and check the EC Dial Angle voltage to see if it changes with the dial operation as @mg2361 suggested in post #3 ?
I did the first time it was messing up and the screen was showing that it was. They have not brought the machine to the shop yet for me to look at this time.
Might not be your problem, but when I first started dealing with these stepper motors 20 years ago I was constantly having to do the relearn across several machines. I found that if you turn the key on and then off while the ecm is running the stepper motor through its cycle (the buzzing and humming you hear in the hydraulic bay) that it confuses the ecm and requires the relearn. I educated the operators and haven't had to do a relearn in years.
Glad to know about that. I may try that first and see what happens.
That was my two cents worth. I have all of the diagnostics that were mentioned by others above. But only in paper form. If that isn't the problem, the component that most commonly fails in the stepper motor is the angle sensor. Sadly, you cannot just get that. You have to buy the entire unit. It is a bit frustrating, like with the rare earth magnets that go bad on caterpillar joysticks, twenty dollar thumb wheel verses a 500 to 900$ joystick. In the time that I have been taking care of these Hitachi/Deere machines (and that is probably a bit over two dozen units) I have only had to replace one ecm. And that was because of a leak in the cabs roof that filled the ECM with water.
Actually, I just remembered this. A couple of years ago I had a Deere 330 that wouldn't idle up. I was sure that it was a stepper motor problem but I was wrong. It was a fuel delivery problem. I had been taking care of this unit for over fifteen years and never realized n that there was more than one fuel filter. This is a long shot, but on all of the zx hitachis that I have dealt with (and an 85 is not one) there is a banjo bolt fitting on the settling bowl that has a pencil filter in it. It is usually placed in the hydraulic bay right by the hydraulic tank.
When it was acting up the first time, I could pull the throttle cable and it would rev up just fine. They should have just put a throttle cable into the cab and not added all the complexity. Don't get me started...
Yeah, sorry about that. I see that you said that in your first post. A few years ago I actually did make a push pull cable to bypass a bad throttle motor on a Komatsu 200. It worked pretty well, it was a bit tricky to get it to throttle up all the way and to get it to throttle down enough to shut off the engine. I made a plate that mounted where the throttle motor was and put a little lever on it. I was pretty sure that I was going to have to go back and adjust it from time to time but it worked for five years until the machine caught fire (unrelated) and got scrapped.