so yesterday I shatter the back window.. today the thumb is intermittent.. in playing around with it the switch seems to possibly the issue.. a quick look in the parts book it appears that the thumb rocker switch on the RH joystick is part of the joystick and not a separate part.. hard to believe I need to replace the joystick to replace the thumb switch.. don't remember the full serial number but starts with FPK and is in the 2K range
Sorry to tell you but you do. The switch is not available separately. Before you condemn it competely you can test the PWM output of the switch provided that you have a multimeter capable of measuring duty cycle.
thx again Nige.. always appreciated.. negative on the meter.. I haven't looked at the connector plug but I wonder if I can disconnect the plug and then wire in a light bulb and battery and see if it makes and breaks or is it more complex than that? I guess it would have to be as the speed that the thumb moves seem to be proportional to the amount the switch is deflected.. ease it just off neutral and the thumb moves slow, full deflection and the thumb moves fast..
Not as easy as that unfortunately. The signal from that switch is PWM (Pulse width modulated). The output is kind of like a square waveform (the Pulse) with a pretty much constant voltage and the width of the waveform is what changes. The signal is measured in "duty cycle" where 0% is one extreme and 100% is the other. Without having actually measured a switch like yours I would imagine the centre position will be 50% duty cycle, around 10% rolled fully one way and around 90% when rolled fully the other way. Oh, and you can't do anything with the plug disconnected. The ECM supplies what's known as a "pull-up voltage" of about 5v on the signal wire coming from the switch so that Diagnostic Codes associated with the signal can be determined. All measuring has to be done by back-probing connector pins while everything is connected. See this illustration. The Y-axis shows voltage, the X-axis is time.
once I realized it was proportional I knew I was out of luck.. as far as the connector plug goes I will check and make sure there’s no corrosion etc after that I’ll probably just wait until it fails completely rather than just shot gunning expensive parts at it.. I’m normally using it at full deflection of the switch open/close.. what leads me to think it’s the switch is that when it fails and I put the switch in neutral and then just move it ever so slightly either direction off neutral it seems to function
A good plan. Always possible to have green crusties in a connector. When a new handle costs somewhere around $600 I think you might be well adivsed to get hold of a suitable multimeter from somewhere and test the operation of the switch you have now. The % duty cycle should change smoothly between the centre value, minimum, and maximum as you move the switch from the centre position.
Good day If you check the PWM valve output (Pressure) you can eliminate hydraulic pilot issue. Kind regards Uffex
thx uffex I'll keep that in mind.. Nige if you wouldn't mind please.. a little help in finding the part number for the joystick.. I've been all through my parts book and it seems like all the sticks with switches are in the 5K plus serial number range.. mine is FPK 02319 the right stick has the thumb rocker mounted vertically on the back side and a small horn button on the front.. nothing else.. the left stick has exactly the same rocker mounted horizontally for the articulating boom and nothing else on the front.. or at least the outer appearances of the boom switch are the same as the thumb.. it looks like there's a lot of different cat sticks you can change just the handle with the switches but doesn't seem to be the case with the mini's.. oh well the parts guys at finning couldn't come up with a part number by serial # but indicated they're normally around 1300 cdn dollars... needless to say it's going to have to quit completely before I do anything in the way of buying parts.. put 2 hours on the machine today and it never failed once..
Tracing it through from the original build data of your particuar Serial Number you have a 280-2956 Control Arrangement which contains a 283-6508 Pilot Control Gp. The PC Gp breaks down into 283-6510 LH & 283-6509 RH joysticks. The handles for those joystick Part Numbers are 283-6512 LH and 283-6511 RH. There is another alternative but I don't think it's the one you have. Take a look at the illustrations below of the LH & RH joysticks respectively. I'm willing to bet yours don't look like this.?
thx Nige I saw those switch arrangements in the IPC as well.. they would look like mine if you took away the round buttons and positioned the rockers down about 1/2 inch on the left and about an equal amount to the right on the right stick..
That’s why I posted the illustrations asking the question for confirmation, because I didn’t think they were yours. What you have for handles are the numbers I posted above - HOWEVER those numbers break down even further......... 283-6512 (LH) breaks down to a 266-3216 Handle 283-6511 (RH) breaks down to a 266-3217 Handle. There is a note against this Part Number stating it contains the "modulation switch", although the switch is not available as a separate part.
Nige, do you know if we feed à contant 12v to à pwm line it is equivalent to 100 %. Looking to build à simple circuit as the thumb doesn't need to be proportional
Unless you provide a Serial Number it’s impossible to say.
BXT04837
Part 266 3217 would be 1500$ canadian
Simplified view of circuit according to electrical schemas
If you go back up the page to Post #4 there are diagrams showing what a PWM signal looks like. Basically it is a square wave of a constant output voltage where the width of the "on" part of the wave gets wider as the PWM signal increases. A PWM output signal % is usually referred to using the term Duty Cycle. Importantly 100% Duty Cycle is NOT a continuous flat line. Supplying 12v on the signal wire would probably fry the guts of the ECM. I would strongly suggest that you don't try it. The supply voltage to the PWM sensor/control is machine voltage, i.e. 12v. I would say that your best bet is to search the web site of a company such as Otto Controls who make PWM devices. They may just manufacture one that works on a 12v input. https://www.otto-controls.com/ Otherwise it will have to be a replacement joystick handle from the OEM.
Suspect ecm (in the handle that take switch input and translate to pwm to solenoids is currently in fault). Looking at options to bypass like sending 12v to selenoid 1 when switch is up an selenoid 2 when switch is down and nothing when in neutral.
Why i think controler is bad 1 start the machine 2 push button up = nothing 3 push button down = thumb is moving one direction and when released, goes opposite direction and able to modulate switch to stop thumb movement but not in neutral position Behavior stays steady until we stop a restart. If we don't touch switch down after a new restart, thumb doesn't move
Do you have a multimeter capable of measuring duty cycle.? If not you need to get hold of one ASAP and check the duty cycle output on wires P978 & P979. Use wire 202 as the ground. When it comes to expensive electronic components "I think" could cost you a lot of money in firing the Parts Cannon without doing the appropriate diagnostics.
Really appreciate your input. If we send constant 12v to selenoid (ex 979 using 202 as groud), would it be equivalent to 100% duty cycle ? According to electrical schematic, 979 goes directly to the selenoid
If you do that you will probably find that the movement of the implement is extremely fast and potentially could be dangerous (that's why they have it proportionally-controlled), but don't let fear stop you..........
Working on a proportionnal circuit using arduino to take the original switch input and translate into 12v pwm. Already managed to get input from switch and generate pwm output. Now need to add the 12v circuit. Will keep you posted on results
Just tested my circuit and it works perfectly. Used 12v leds to test at home (see video) and confirmed on excavator today. Next step is to put it in epoxy for water and vibration proofing. Just saved 1500$ cad.
so the thumb has worked flawless for the last 6 months and then out of the blue it went intermittent for a day and now it's fine again... I've got hard copy maintenance manuals but no electrical schematic.. Nige is there any chance you could dig me up a schematic for the thumb.. until it completely fails I'm going to just keep driving it but I'd like to check any connectors in the system first.. thx much serial # FPK 02319
Check your message inbox.
thanks much Nige.. really appreciate your help
this is fantastic! I don't have a Cat, but there should be a place where people keep track of the schematics for bypass solutions like this which they make to keep their gear running.
still dealing with an intermittent thumb.. works flawless for months and then gives me fits for a couple days and then back to being fine.. pretty hard to troubleshoot when it's not failed.. just trying to get my head around the location of the other components in the system.. is the electric controller in the handle? or? I'm assuming the hydraulic control valve would be on the main block with all the other valves.. the wiring diagram threw me for a loop initially as it's in error.. it shows the boom swing PWM switch being on the RH stick and the Aux (thumb) being on the LH
Is the Publication reference of the electrical schematic you are using RENR9638-01.?
yes it is Nige.. it's the one you sent me about a year ago.. I don't find it particularly user friendly.. I have trouble trying to figure it out.. I'm used to aircraft wiring diagrams.. lots of detail I was hoping to find any other connector locations as well as where the control module and control valve locations were
That's strange. When I click on the blue hyperlink (B) above the boom swing switch it takes me to the area of the LH joystick. The whole schematic is hyperlinked. Click on a component or a main harness connector and it should jump you straight to an illustration showing its location on the machine. Notes explaining the hyperlinks are right there on Page 1 of the schematic. You really need a Parts Manual for that level of detail.
in the diagram there's a note that says A is left stick and B is right.. no biggee I clicked on the blue highlights on the wiring diagram and nothing opened.. I'll try it on my iPad later and see what that does in the meantime the thumb works just fine
Maybe I’m missing something
You're not. That nomenclature is wrong. Locations B and A are interchanged. TBH I never spotted that because from past experience I simply jumped straight to the hyperlinks (see Post #33 above) which are in fact correct. The only time I start looking for notes like the one you highlighted is in the case of an older schematic that does not contain hyperlinks. All I can guarantee is that the hyperlinks work when the Adobe pdf file is viewed on a PC. Have not tried them on a phone or even a tablet.
well I guess the hyper links don’t like anything apple… guess I’ll need to find a PC somewhere.. I’ll ask finning if they have a Mac friendly link
so after lots of time on eBay I've conversed with a couple places in china that would repair my stick (if in fact that is actually the issue) or provide a new aftermarket unit.. the aftermarket is about $200 cheaper than one from finning.. for that kind of price difference I wouldn't consider aftermarket.. the choker is just the handle with switches (horn and thumb) from finning is $1400 CDN.. one thing I did find out from the conversations was that there is a circuit board inside the handle along with the switch.. looking in my parts and service manual I've discovered that the pilot valve arrangement is located under the floor just about under where my left foot sits.. just for giggles I'll disconnect the connectors there and make sure they're clean.. what makes it hard to track this stuff is that the machine came from the factory all plumbed and wired for a thumb but did not have one installed.. the thumb itself is aftermarket.. what the manual references for all the installed stuff is "auxiliary" and this makes it hard to chase.. oh well.. one day it may fail completely and then troubleshooting can begin in earnest until then it can just remain intermittent
OEM doesn’t look that bad price-wise now does it.? TBH you’d be well advised to make sure that the joystick and its associated electronics is actually the problem before you go splashing out on a replacement.
there's days I wish it would just fail and stay failed... take all the guess work out of it.. I really don't plan on spending that kind of coin just on the off chance.. different story if the handle was a couple hundred bucks.. if it continues to only go intermittent once or twice a year I can deal with that.. in the mean time I'll continue to educate myself on how it works and where the components are located