G'day all A local contractor in town has purchased a MM55SR painted up in Cat colours, but I think it may be a Mitsubishi, either way it is a grey import as E1G00xx prefix doesn’t come up as a good serial # with Cat dealer. My mate needs to find a few parts, his biggest problem is that the hyd don’t work when levers are used, but if you move control valve direct they with work. The electronic hand control system seems to be the problem, anyone had any experience with these machines or this problem? thanks in advance
Part request mm55sr Is there a way to find part for this excavator? In usa or canada?? Nachi Hydraulic pump ? ? If someone know something please help us me and Fred. Thanks:notworthy
A friend of me who owns a mitsubishi 5 ton excavator here in my country, replaced the electronic hand control to usual hydraulic controls because he could not find any parts. Of course he paid enough money... I also have a c a t graymm and the only way to find parts is to use serials from cat catalogue. So, you have to find out the similar to yours cat machine and match the parts serial. But this is also riski because serials do not always fit to the gray machines.
That is a rebranded mitsubishi...as for the problem,is there a bad switch in the pilot enable lever perhaps?
Ive seen that brand on smaller deere and hitachi excavators,mostly on valving though.
Hi I have the same problem with my 55. The rams operated by the electrics keep cutting out. Did you ever find a solution.
Does anyone know where you can get parts for an MM55SR? Cat is no help and have not been able to find any parts. I'd love to have any service info anyone has. I have a schematic for the MM55SR if anyone needs it.
Have you tried Maxis corp. Maxis.jp they are in Japan but have been helpful with my MM30SR
No parts needed so far, joysticks stopped working but soldered a new ground on computer and all is well.
I own a mm40sr and i have the same problem have found another thread on "mm30sr" full of people withthe same issues. as far as i can tell they are very simmilar electronicly. I have some error code sheets for these machines but am still at a loss for parts or help.
Wayne I'd be interested in the code sheets if you can send them. I have schematics if you'd like them.
that would be great. send me your email eddress i will forward them to you. & i would be very greatfull to know more about were to solder a new earth wire to on the circuit board. a photo or instruction on the process would be fantastic.
my direct email address is [email protected] happy to help anyone who needs the info & code sheets i have.
Mm55sr Can you send me the schematic foor the MM55SR. I have a problem with my machine
MM55SR Controller Retrofit kit We have been supplying controller replacement kits for the MM55SR since 2009. The controller is a non-computer based box, converting the Mitsubishi joystick signals, matched to control the proportional valves. The retrofit is simple, basically bypassing the old loom and using only the existing valve and joystick connections. Please contact me [email protected] for details
Steve here wanting to purchase mm55sr controller kit can I have contact number for you please
Graham any chance i could get a copy of the schematic? I have the same problem with a MM55SR that the joystick controls wont work.
Graham, we would very much appreciate a copy of an electrical schematic for the mm55sr if you can help thanks. deep southcc
I know this is old but I have the same problem , where did you find a broken ground ?
mm55sr controller retrofit kit, help!!! glad i finally found other people with the same problem, can you email me with a price and availability to the U.S. thanks kevin.
[email protected] guess the email address would help
I FINALLY (after about 5 years) have a ENGLISH service MANUAL and parts book. I also had a Japanese friend translate some of the marking on the machine (control buttons on the LCD AND the fuse panel). If anyone is interested in purchasing (I spent countless hours and lots of money having this translated) you can email [email protected] . Email me for a phone number as well if you like and we can chat. I would also be willing to trade for some other mm55sr knowledge OR some other help with it, or parts.
Hi from NZ Any chance of a schematic for mitsi and location of the computer earth that needs repair Thanks Johno2
If you are wanting to bypass your Monitor Controller, have a look here where I posted a step by step:
GGGraham, I am in need of schematics and error codes if you still have avail. Have electrical short on many engine wires. Need to replace and troubleshoot. Thanks in advance.....Randy
did you find wiring diagrams i am also looking for them as well as hydraulic valve flow diagrams
Yes, I have found diagrams thanks to the folks on this forumn. Email me [email protected] and I can forward to you...Randy
i have same problem with my mm5sr it would be great if someone can send be the schematics! Thank you in advance
hi i would like to have the schematics if possible! thankyou for you time
i need the schematics please any one that can help dm me
I have some manuals etc... not sure if they will help. Email me at [email protected]
This thread's been running a while but I'm hopeful of some help with my MM55SR. I have a problem where the boom won't lower. I've done a lot of diagnosis on this and came the the conclusion that is was likely a controller fault so decided to replace the controller with one from Tony and IMDynamics in Australia. The changeover was reasonably straight forward but the unfortunate thing is that it did not fix the fault, the boom still wont lower! I can lower the boom by manually operating the valve so the issue has to be with the mechanism operated by the electromagnetic coils on that valve. Has anyone had an experience of these valves and how they function? Any advice would be appreciated. Thanks
Did you try pressing the button under seat? if not, get someone to hold the button down and see what happens. Let me know...
Yes I tried that at the very start of the diagnosis of this fault a way back when along with a number of other things. In the end I found a number of odd things and decided to replace the controller and take them out if the equation. The old controller is now disconnected so it has no part to play any more. The new IMD controller is installed and working well. But unfortunately I still have a boom that won't go down. I'm need information about the physical working of the main control valve block particularly how the electromagnet coils make the main valves operate and, more importantly, what would cause them to fail. Chéers.
Have you checked the boom spool valve coil resistances and if there is voltage going to them when you operate the boom? Graham.
Yes Graham I checked that and it is the correct resistance of 9 ohms. I have found the fault though. The coils sit on what in known as the solenoid valve, you can see them in the attached picture. I carefully dismantled and cleaned the inner workings of the valve in case it had become blocked with some dirt in the oil. The two posts you can see are the boom up and down valves actors. Inside those posts are a pin that is forced down to activate the valve when power flows through the coil. I tested them both when dismantled to find the down valve actor post does not work. The pin does not move when power is applied. Swapping the posts around and reassembling confirmed this. I now have no up boom action but down boom works
Hi Pete, I'd be very interested to know how you get on with fixing this. I have a parts manuals for the MM50SR if you are interested. Your valve part seems to be part number PA4342. Graham
Hi Graham, Yes I we've exchanged a few emails about manuals. I have that parts manual too. I could not track down the part new so bought a complete valve bank from a wrecked digger. It's a bit of an overkill but Ill have plenty of hard to find spares should I need anything else or anyone else need anything for that matter.
Hi guys, Would it be possible to enter this thread too? I have an mm55sr, and i am having the same issues. I could use the wiring diagram, and hydraulic system info too. Can someone email it to me at [email protected] ?
I am interested. Please e-mail me at [email protected] . Thanks
I am looking fro this same option. Can I get some information on it? Thank You.
I've put all my information re Mitsubishi MM30/40/50 series machines on my website which has electrical details, fault codes, parts manual, engine manuals etc. It's not complete but always interested to add stuff to it. Hope you find what you need https://www.woodandtrees.co.uk/
Do you have any pictures of where and how you soldered the ground? It would be much obliged.
Hi graham could you please send me the service and parts manual. [email protected] Cheers Aidan
Hi Aidan, I've sent a reply to your email with the details. If anyone else needs them they can be found on my website https://www.woodandtrees.co.uk/ cheers
Switched it all over to the cable controls that are used on a masy Ferguson tractor. Got rid of all the electronics works great!
Great photo. Have got any more, particularly of the joystick arrangement. I'm always interested to see what to do if the electronics fails.
View attachment 302652
Removed all electronic and wireing, just the basic stuff
Hello I would like to get my hands on the service manual. Are you able to help? Mitsubishi mm55sr. Thank you in advance if you are able to.
Hi - I have tried to reach out to the emails on this thread with no luck. Did anyone ever get the ENGLISH MM55SR manual and parts book from Aksobe? If you have it, I would love to get a copy along with anything other documentation related specifically to the MM55SR. Happy to pay Aksobe for it but reached out via email and no response.
Scott, have a look at my website and open the Dropbox links under the MM30 etc tabs. This should cover most of what you are looking for. cheers G Life in the Woods www.woodandtrees.co.uk
⚠️ WARNING: Avoid IMD – $4000 Controller Failure, No Support, and Now I’m Building an Open-Source Replacement Hi all, I want to share my experience with IMD (IMDynamics) and why I strongly advise you do not buy their MM-R controller system , especially for excavator control retrofits like the Mitsubishi MM55SR. Why I Went with IMD I have a background in automation and system integration. When my excavator needed a modern proportional joystick controller, I thought: So I went ahead and ordered their MM-R system — a decision I now regret. ❌ What Happened After spending over $4000 NZD , I installed the system — and ran straight into major issues: Proportional joystick response is sluggish and non-linear Solenoids hammer and buzz violently — no matter the settings The system lacks the finesse and feel needed for accurate digging I followed every instruction and even ran their joystick calibration tool — no change. Trying to solve the issue, I went above and beyond: Sent them detailed voltage readings Shared joystick outputs in neutral and active states Provided photos of settings, wiring, and system behavior Tony from IMD even admitted that some customers had experienced the same issues — but since then, they’ve stopped replying. It’s been over two weeks with zero communication , even though they know I'm based overseas and likely can't do much about it. What I’m Doing Now Since I’m not getting any support, I’ve decided to build my own open-source replacement using modern, accessible components. I've already ordered the parts to build: A Teensy 4.1-based PWM controller Logic-level MOSFET drivers for the 12 V solenoids A touchscreen interface for settings and calibration Full safety and fine-tune logic: deadzones, curves, neutral switch, etc. The entire build will cost $400–$500 NZD total , and will be better-performing than IMD’s system with actual support. Bottom Line If you're considering buying from IMD — don’t . They may look like a professional outfit, but when things go wrong, you’re on your own — especially if you’re not local. I made the mistake of trusting them instead of building my own solution. Now I’m fixing that, and I’ll be sharing every step of the way to make sure no one else gets caught the same way.
Thanks Naved we were just about to buy from them. We are also in NZ after reading this we won't be. If you can post what you do with your MM55 we have one as well we would like to sort .