EX 120-3 Electrical Problems

[rtcw37]

Hi I am new to the site.And was looking for some advice.I have an EX 120-3 and it suddenly stoped and engine cut out.We were sure it was diesel problems, but the diesel system is working fine.The ignition is now trying to start the machine in stage 2 ignition, which is when the machine should be doing its pre checks before, the heater plug lights go out, and then you proceed to stage 3 and machine would start normalyThe machine turns over and over, but will not start or even give an indication that it wants to fire up.Any ideas as to what is causing this and not allowing the machine to start.Any help greatfully appreciated.
Thanks Pat

 

[spitzair]

I think something in your shutdown system has failed. I don't know where all the pieces are on a 120-3 but in the EX 100-2 manual it says the following : "The engine is stopped using the key switch. Moving the key switch to the OFF position causes the E.C. motor to return the governor lever to the stop position, restricting the flow of fuel to the engine below the amount necessary to maintain operation. In addition, the emergency relay is activated, which in turn activates the stop motor, cutting off the fuel flow to the engine." I'd start by trying to manually move the governor lever while somebody cranks the engine and see if that helps. If it does then you can trace the problem further. Hope this helps!

 

[rtcw37]

RE mail

I think something in your shutdown system has failed. I don't know where all the pieces are on a 120-3 but in the EX 100-2 manual it says the following : "The engine is stopped using the key switch. Moving the key switch to the OFF position causes the E.C. motor to return the governor lever to the stop position, restricting the flow of fuel to the engine below the amount necessary to maintain operation. In addition, the emergency relay is activated, which in turn activates the stop motor, cutting off the fuel flow to the engine." I'd start by trying to manually move the governor lever while somebody cranks the engine and see if that helps. If it does then you can trace the problem further. Hope this helps!

Hi And thanks for replying to my call for help.I dont know what the Governor is i guess that is what we here in Ireland call a solenoid.Maybe i am wrong.It is taking a live feed from somewhere either the wires are bared or shorting or the ignition switch or the starter relay are gone faulty.Does it say anything about these problems in the EX 100 manual.Or have you ever encountered this.Thanks again Pat

 

[eric12]

it might have a fuel shut off solenoid. if it does you could try to disconnect the linkage connected to it and hold it open then try and start it. does the ignition work how it should? you made it sorta sound like its not working properly? does the motor turn over and just not start?

 

[spitzair]

Not exactly sure how much this will help you but it's what I found in my manual for the 100-2... I would imagine yours to be similar. I've circled the governor control lever in red, you'll want to find this and disconnect the cable on it, then manually move it and see if the machine starts. If it does, then the problem is somewhere in the electrical side of things, if not, then it's a fuel issue. Actually before you disconnect anything, have someone sit in the cab and turn the key on to see if it moves... If it doesn't move, then go ahead with disconnecting and manually moving the lever... Hope this helps...

 

[eric12]

if your in the cab you should hear the fuel solenoid click as you turn the ignition on. thats probably the easiest place to start.

 

[rtcw37]

Hi And thanks Spitzair and Eric12. The ignition was faulty and a new one fitted today.When you turn it on to stage 2 the machine starts to turn over which should not happen till one turns the Key fully clockwise, and the key is then released back to stage to when the dump relay and surge relays open to energise the circuit.I disconnected the starter solenoid to see if it was faulty and the machine still tries to turn over but no start,I disconnected the main lead to starter, reconnected it and the problem disappeared all but temporarily.I crossed the the connections got the machine started while also holding the throtle control lever open but the machine had no power to and woulld not run correctly and barly had power to track or move the dipper and boom.It has me totaly stumped.It is electrical but where do i start?Thanks again for the replys guys it is of great help, will get to the bottom of it i know but it is frustrating.Thanks again Pat

 

[eric12]

How do you know the ignition was bad? If the problem isn't solved with a new ignition maybe that wasn't the problem? Also are any fuses popped? Look around the wiring harness near the starter where you moved it last time to see if you have a short or broken wire. I had a similar problem with an excavator on and off for a year, I replaced the ignition and it got better then didn't work again and it turned out to be a broken wire.

 

[rtcw37]

Hi eric12.I checked the ignition it has been faulty for a while, so had to replace it anyway and was sure it was part of the problem but unfortunatley not.Its a head scratcher this one Thanks Pat

 

[shopguy]

So the starter runs with the small wires to it disconected ?

 

[dodgeram22871]

hi rtccw37 i am in cork heres my number 086 8293385 give me a shout ,kevin spillane

 

[spitzair]

I think there's a diode in your alternator circuit somewhere that is supposed to allow power to the starter when the engine isn't running and then stops/opens the circuit when it's generating power, ie the engine is running. This is supposed to keep you from engaging the starter with the engine running. I'm not sure if your machine has this but I've heard of it on other hitachi machines of the era, perhaps your diode is fried allowing current to the starter making it run as soon as you turn your ignition on... I'll root around in the wiring diagram of the 200-2 (only one I have) and see if there's one in there... Hope you're making some progress.

 

[rtcw37]

Hi spitzair, Thanks for all the help.I have got to the bottom of the problem i think,The solenoid has gone faulty and was staying on continuously.Usualy they dont engage, they usualy close and wont engage the starter, but mine has stayed engaged all the time, so it would not start the machine, because the computer and diode were not able to recognise, that the solenoid was faulty the diode would not create the open circuit, allowing the ECU and Throtle to engage the machine would not start.It is a failsafe on the machine to stop the starter from getting burnt out if the solenoid or diodes got faulty and keep trying to start the starter thus causing failure.Thanks once again Pat

 

[spitzair]

Hi spitzair, Thanks for all the help.I have got to the bottom of the problem i think,The solenoid has gone faulty and was staying on continuously.Usualy they dont engage, they usualy close and wont engage the starter, but mine has stayed engaged all the time, so it would not start the machine, because the computer and diode were not able to recognise, that the solenoid was faulty the diode would not create the open circuit, allowing the ECU and Throtle to engage the machine would not start.It is a failsafe on the machine to stop the starter from getting burnt out if the solenoid or diodes got faulty and keep trying to start the starter thus causing failure.Thanks once again Pat

Hey anytime, that's what we're here for! Glad you got it fixed. And thanks for posting what the problem was, I'm sure it'll help others with the same problem at some point...

 

[rtcw37]

HI spitzair, thanks again.The Hitachi EX120-3s give alot of trouble compared to the dash 1 and 5.The 2,3and 4s were only half the machines of the 1 and 5 but i had to discover this after i purchased my dash 3. I have encountered alot of problems so if anyone has problems with them i might be able to help from experience.Regards to you all it is a great site and keep up all the good work.Thanks Pat

 

[rtcw37]

Hi spitzair, The starter was fitted today but the problem still exists the starter solenoid problem is gone but the machine will not start.It keeps turning over the starter, the only way i can get the machine to start is to get someone to push the throtle linkage at the engine control motor, the machine starts after the linkage is moved a little, the machine throtles up but the machine has no power and the idle, economy, power, and full throtle buttons do not move i am at a loss,i wonder if there is a power relay that got fried when the starter surged or ie the computer gone faulty.I cant figure it out i am scratching my head.Have you any ideas?
Thanks Pat.

 

[rgl726]

you have an EC problem.

probable cause:

1. short circuit of the throttle motor harness or throttle motor itself.
2. if the harness or motor is short circuited the throttle motor servo controller in EC will be damage.
3. you need to replace the EC.

 

[rtcw37]

Hi rgl726. Thanks for reply.I am going to test the electrics in the EC, the fuses and the Throtle control motor.I have a special tester that can load circuits without damaging the electrics, I can check for short circuits and power circuits through the tester, so hopefuly i will come to a sucessful outcome.If the EC is faulty i will check the PCB for damage and replace the shorted circuit or resistors and check it in the machine to see if it works if not i will have to purchase a new one which will cost a couple of hundred euros, which i would rather not have to pay so i will try to fix.Thanks Again Pat

 

[spitzair]

Be careful where you apply power with your tester, most of the computerized system runs at a significantly lower voltage than the rest of the electrical system if I'm not mistaken. On my 200-2 the power buttons don't do anything either, and, like rgl726 says, the Engine Controller (EC) is probably fried, mine is. I have a manual throttle on my machine, and it works fine this way. I'm not sure if you'll be able to fix your computer, I tried to fix my PVC, took it to an electronics repair guru and he wasn't able to fix it either... I ended up buying a new one and completely rewiring my entire machine. https://www.heavyequipmentforums.co...-Hitachi-EX200-2-computer-question&highlight= Here you'll find my story with the machine and the outcome... Check your fuses to see if any are popped. On a -2 machine, at least according to my manual, fuse #2 is for the engine controller and is a 1 amp fuse Fuse #3 is for the throttle control motor and is a 5 amp fuse, and fuse #14 is for the stop motor, also a 5 amp fuse. Whatever you do DO NOT put a bigger fuse in these spots than what the book calls for or you WILL blow up expensive pieces! Don't ask me how I know that... Once you have confirmed your fuses are good, look through the little round window on your computer. There's a little L.E.D. in there that will blink on and off steadily if the computer is working. If there's no blinking light that means the computer is not working, so could be no power to the computer or the computer is fried... Some poking around with your tester will tell you if you have power at the computer plug. Hope this helps. Good luck!

 

[Murrayg]

Hi
I just bought a EX Hitachi-3, do you have a copy of the manual?