I just got a Link Belt 2800Q that had a throttle control problem before I got it. Each time I ran it, it started off normal and the problem showed up after a few min. The throttle would act normal, one touch idle also, until at some point it would become unresponsive. The backup throttle control would not move it when the problem was occurring, however it would under normal conditions. Electrical problem would show on the screen and 0000 on the clock. I used the attached pages for a JCB that I found on here to test the throttle motor and the control box and they look ok. I opened up the main computer and I can't see any burns or cracked connections. I found some chewed insulation and am in the process of tracing the wiring. I can't get a couple to connect and I was hoping someone may have an electrical schematic they could get to me. I got a manual off of eBay with one, but it must be wrong, because it doesn't show the throttle control module on it. Of course, this machine is the same as the Case 9030 series and Sumitomo and JCB. Any help would be very appreciated!
I'm really not familiar with the link belt but I have worked on the Case machines. Is this a square body machine? Does the throttle motor cycle when the key is turned on without starting engine? Can you post a pic of machine?
Thanks for the reply! Yes, the throttle cycles to find the limit when the key is turned on. I've been troubleshooting quite a bit. If you think you'll be able to help, I can try to explain more about what I've found.
Here are some more pics. I've ohmed the wires and checked for faults to each other and to the frame and can't find anything. I think I get the signal from CN8-2 (drops out 5v then comes back to 5v when the error message comes in), but can't tell for sure if the pulses are going out of the motor control box to the stepper motor. It seems like here are only 2 coils that are staying energized, but not sure. I get a Hz reading on all 4 of them I think until the error comes in, but not a voltage change (may be too fast to read) The stepper motor ohms out right, and the lever to the cable moves freely by hand (disconnected from the fuel pump). The motor stays locked in place by the power when the key is on. Can turn off key and move to a different position and back on and it will hold it there. Each time the throttle has worked, it always worked normal (usually 10 to 20 min) until the fault came in then usually would not go away till the next day. It's not working at all at any time now since I was trouble shooting and moving it a lot and I guess I broke it for good. It never has been erratic, just not worked. I'm considering buying a new throttle control box or seeing how much I could get them checked out by a circuit board place.
Thanks for the pics it looks like your machine is the same as the Case 9030B I would check the relays that you see there and ohm the wires for the throttle driver. Also check all your fuses because some fuses that are marked spare aren't really spare they are used for different purposes. If I can find my old school books I can walk you through the advanced diagnostics.
Ok, I'll check out the fuses and the relays. I know which relay closes when you select the back up throttle, but don't know how it works. Maybe you can give information on how it works in the system. Also, any time the regular throttle stooped working, the manual throttle would not work either. I checked the throttle dial with a meter and it looks ok. That'd be great if you could get me some info from the case books. I'd even be interested in buying them if they have the right information for my machine.
Any luck finding your manuals? Do you think it could be a problem somewhere else causing this? Like a bad sensor or a short in the alternator (someone mentioned for this problem in another post)? However, the backup throttle stops working at the same time the normal throttle does.
It very well could be a bad sensor or wire in the harness. I haven't found my books as of yet but still looking. There is a cover at the back of the inst. cluster that is held on with two tiny screws, these screws are aluminum so don't loose them. When you remove the cover you will see four buttons these are for the advanced diagnostics and there is a procedure for getting into this and I can't remember how to do it right now. I will try and find out asap for you.
Check out the 4th post. HeavyEquipmentForums
I'll try the diagnostic like the post says. Will the error be plan words or some code that I need info to translate? Thank a lot for taking the time to look for the books.
Check your wiring harness for corrosion into cab base also if you are loosing back up as well i would be inclined to check the wiring and continuity in loom as well to make sure every thing is ok but check in hyd pump bay for wiring being a bit crisp and hard ans are prone to cracking or at least on the JCB version. Motor drivers fail i have posted a flow chart previously for this to prove if the driver is suspect. Check battery isolator as these can give you all sorts of electrical issues they have 2 diodes in them work a look. I guess you have pinned the the feed from the ign circuit as you would need this into the controller and that you have not got a faulty switch or wiring as you should have redundant circuit at least if the controller goes down. This makes me think you need to perhaps look at the loom.
I have the exact same problem. Setting out to troubleshoot the issue this week. Can someone tell me where the "controller" in the picture below is located. I know where everything else is. Thanks in advance
The controller is the main computer. Both the main controller and the throttle control box are behind the seat. I have had any time to work on mine so let me know if you figure anything out.
In case anyone comes across this thread later, it looks like a new throttle controller computer (KHR1885) solved the problem for me. I made a new wiring harness and that didn't solve it. When the issue would occur, neither the regular or the manual throttle would work, and the motor ohmed good so that pointed to the computer. I probed the 4 leads going to the motor and I would get different readings when the problem was occurring vs when it was working normal, so went ahead and replaced it.
Three years was a long time for a machine to sit. Hopefully you don't find more problems.