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Tilt and Lift not working on Bobcat 863

Discussion in 'Skid Steers' started by Axel, Dec 22, 2014.

  1. kilohertz

    kilohertz Member

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    BC
    Until I find wiring diagrams I am going to have to ask some questions to understand the system. Does the AHC computer drive the BICS, ie does the AHC go thru it's self test and then say "hey, I'm good, you can activate the tilt/lift valve" or does the BICS computer go thru it's test, looking for everything to be in order, then it gives the green light to the AHC box?

    Ran it around the yard and up and down the driveway and it didn't fail again. With it's history and all new actuators and sticks, I'm leaning to something missed by the dealer and like your issue, a relay, fuse holder or rubbed wires.

    Thanks for the help.

    PS, just found the little plastic operators manual in the side box and I see that 5 blinks means actuator at fault, mine being the tilt actuator. If I understand correctly, the actuator is simply a motor and pot, motor 2 wires and pot 3 wires, still could be wiring harness as there are 5 wires to fail there. :) Just need to finish my job with the 853 this week and then I'll be able to dive into the 863.
     
    Last edited: Apr 21, 2017
  2. kilohertz

    kilohertz Member

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    One other comment, in my diagnosing the 853, I have found the BICS to be very sensitive to power supply voltage, ie when I start the engine, if it cranks too long, even though all 4 lights were on when the cranking started, once the engine starts, if the main 12V line drops too much, the BICS craps out and complains and looses it's brain, some lights stay on, others go out. Shut down, start right up again with less cranking and away it goes, happy happy, all lights on. I was thinking of adding a capacitor right at the BICS to help hold the voltage up while cranking, but the root cause is probably still some bad connections somewhere between the battery, and the BICS. Food for thought.

    Yet another PS..just thinking about which computer drives which computer, if the flashing LEDS are on on the sticks, that would tell me that the AHC computer senses a fault, and thus is keeping the BICS from turning on. This machine is a little more complex than the 853. The BICS needs confirmation of safety bar down, operator in seat (853), and it seems, an okay signal from the AHC computer, in order to activate the solenoid for lift/tilt.
     
    Last edited: Apr 21, 2017
  3. kilohertz

    kilohertz Member

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    Another update...after getting it off the trailer and running it around, I discovered that it was only failing when using the bucket curl, not lift or bucket dump, just curl. Repeatable multiple times, I could start the machine, lift, tilt down, the moment I hinted at curl or tilt up, fail, right light on left stick flashing 5 times.

    So when I got home tonight I raised the cab and steam cleaned the underside getting ready for troubleshooting. Was actually pretty clean once I removed all the dirt and fluid muck. AHC harness has been changed, update kit installed, controller replaced and sticks replaced, all within the last 3 years. After I finished pressure washing it I decided to do a quick diagnostic and pulled the actuator plugs and cleaned the pins and sockets, just blasted a little WD40 in there, they were damp from the wash. I then unplugged the big round socket/plug right at the back of the cab's bottom side and reconnected it. Looks like the AHC wires run thru that big plug, and down to the AHC controller, thru another one of those big circular plugs.

    Well between the cleaning and plug disconnecting, I have not had a single failure tonight. Ran it around for a while, then shut it down and did it all again 4 times, no failures. Seems the issues are in the plugs/connectors.

    Hopefully this is all it needs. I was pretty amazed at the poor choice of connectors made by Bobcat. The pins are barely large enough to support 2 or 3 amps, little dinky pins and sockets. I much prefer the older blue/black connectors of the 50 series machines, larger pins, better connections and higher power handling. Oh well, I just fix 'em, I don't spec 'em. Will for sure have to properly waterproof them if this turns out to be the issue.

    Cheers
     
  4. Axel

    Axel Well-Known Member

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    Well it rained quite a bit last night and the 863 is bugging out. worked for a while then hesitated for a while then worked etc...
    I alternate between using the BICS bypass I created and the original setup. sometimes one works, sometimes the other, sometimes neither.
    Most of the connectors I ever checked look like new inside, and all have been dry.
    The 5 flash on the sticks can indeed mean bad actuator.
    A quick check is to switch harnesses and see if the problem transfers. However it can also mead bad ground....... seemingly infinite possibilities.
    In my case the code shows up on both sides. I have a brand new actuator and brand new $500 AHC harness.
    sometimes both lights are flashing like it's christmas while everything is working great.
     
  5. kilohertz

    kilohertz Member

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    Thanks for the update. I worked all day on my machine. I completely cleaned each connector on the machine, including the 2 big circular connectors that go the AHC controller and the one at the back of the cab, like yours, they look pretty much like new inside. Then I removed and cleaned all the grounds on the starter, 3 big 10ga wires. Also cleaned all 8 fuses and holders at the back, bottom right corner of the engine bay. All wiring harnesses look great, all safe inside the split covering, no visible rubs or problem areas. Started and drove it around for a while with no issues, great! It's fixed. Tried it a few times and no problem. Decided to detail the machine, even used Armour All on the gauge pods and seat, machine looks great. Anyone ever detailed a Bobcat? :) Then decided to grease all the fittings, went to curl the bucket to get at the fitting.............................and it crapped out. DAMNMIT!!!! Only did it once, but it was enough to discourage me. Started raining so I came inside and am having a beer and watching the hockey game.

    Still something not right....we'll get it.
     
  6. kilohertz

    kilohertz Member

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    One other thing I noticed while I was playing around with the sticks, various movements trying to get it to fail.....

    If I hold a stick slightly off center before activating the hydraulics, I get and error code (flashing LED in the handle), but, it's not symmetrical. If I hold the tilt stick just a hair towards the center (curl) I get the error, if I hold the stick way off center (dump) I can activate the hydraulics, not get the error, and the bucket actually starts moving as soon as I press the operate button. Seems to me like the potentiometer is not centered in the stick. I also noticed the same phenomenon in the lift stick, and my sticks are new. I wonder if they should be dismantled and re-centered?

    Food for thought.
     
  7. BC873G

    BC873G Member

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    Location:
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    Hey kilohertz, I have a similar issue with an 873G. Have you been able to resolve your problem? If so, what was the fix, and if not, any thing else you have tried?

    Cheers!
     
  8. kilohertz

    kilohertz Member

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    Hey Kansas,

    Yes I have tried many things, and thought I had it nailed...was working flawless for 3 weeks then all of a sudden started acting up again, only tilt fault again.

    What I did was removed both actuators, reset the neutral position of the tilt actuator by taking the gear cover off and moving the sensor gear a few teeth, to get the actuator to be recessed to about .2" into the housing, when centered. Also swapped tilt with lift actuator to see if the problem would move. Also found that when I was installing the actuators, the little pin with the ball on it, seemed to wiggle out of center just while I was installing the actuator, which made me think maybe it was wiggling out and binding on the teflon sleeve groove...then I noticed that the end of the spool valve has a flat on it, so I thought that maybe the pin should be installed in such a manner that the little ball sits in the gap between the spool and actuator. Shazamm! I thought, that must be it. well it worked for 3 weeks and now it is acting up again.

    Last week when it crapped out, I noticed that when I powered up the AHC system, without the engine running, I could hear the actuators operating, but the tilt was only moving in the dump direction, not curl, and it sounded much slower than the lift actuator. Then the tilt quit completely, no actuator movement at all so I raised the cab and swapped the actuator harness connections, the tilt actuator still wouldn't move, so I wacked it with a ratchet and it suddenly popped back to life. Worked about 80% of the rest of the day, maybe one or 2 more failures. I still don't think it is the actuators as they are all new about 400-500 hours ago (changed twice in 2 years), plus I had swapped them 3 weeks ago, harness has been changed, new joysticks, new AHC controller, joystick upgrade etc. It's always the tilt that fails.

    So I am now thinking that after the previous owner spent $10K trying to get this fixed, and the local Bobcat dealer hasn't been able to fix it, it must be something in the hydraulic block, the spool is binding, folded over or damaged o-ring, something inside the hydraulic section that is causing the spool to bind or get sticky...something that if it had foot pedals, you wouldn't even notice as there is so much force available from your foot, but the poor little actuators with a little .9A motor will crap out at the littlest bit of resistance. When I get the machine back to my shop I will pull the spool valve and see what's going on in there.

    Keep you posted.

    Cheers
     
  9. BC873G

    BC873G Member

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    Hey kilo, I think I found my issue. There was a socket inside the connector that goes between the lift handle sensor and the AHC controller (3 pin, red, black, and green). On the controller side I found that the socket for the positive voltage had a bad crimp and might not have been seated deep enough in the connector. The pin from the lift handle sensor was very loose. I couldn't see that until I took the connector apart and inserted each pin into the sockets. I made a video of the repair if you want to check it out:



    I've finished up last weekend and have run now for a couple of hours with out throwing a code. I still can't explain why the error would happen only when I operated the lift and tilt at the same time. I consistently got the 32-40 error though.

    I did have leaking spool rod seals so replaced those as well. Plan to make a video of that as well.

    Regards for Kansas
     
  10. kilohertz

    kilohertz Member

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    Cool, your machine must be newer, I don't have any "codes" as I just have 3 analog gauges, no BOSS or modern equivalent. My machine is still on site and should have it back at my shop in a few days. My connectors have 10 pins?? going to each actuator, on the joystick there are 3 to the joystick pot, but my harness has been changed as well as the joysticks...maybe they had a bad run of harnesses. I will check that before dismantling the hydraulic system.

    Thanks for the update.

    Cheers
     
  11. BC873G

    BC873G Member

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    Location:
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    Yes, I have a new machine with the deluxe instrument panel which can display error codes. BTW, I had a similar issue with the lift actuator running when I powered on the machine and pushed the PTO button. I could also make that happen when I wiggled the 3 wires right before the connector. Note that my issue was with the 3 wire connector that comes from the handle sensor going to the AHC controller and not between the controller and the actuator. If you are getting some uncommanded tilt you might consider swapping the handle sensors and see if the issue moves with the handle sensor. The handle sensors on my machine are the same.

    Even though the handle harness was changed out they probably reused the connector and probably only removed the pins on the handle side of the connector. I would try removing the sockets on the controller side of the connector and the pins on the handle side of the connector and see how tight they fit together. Or, at least push those rubber round seals as deep as possible into the connector and see if that provides a better connection and prevents the uncommanded curl with your tilt.

    If you dig into the control valve I found it really nice to remove the control panel and raise the lift boom. You have a lot room to work from the top side and it makes it a lot easier to see the wire harness. It doesn't take that long to remove the control panel. Do you have a service manual for your machine?

    Good luck.
     
  12. BC873G

    BC873G Member

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    Axle, what reference did the attachment come out of? I would to have something similar for my 873G and my service manual doesn't provide any reference for this kind of information. The neutral voltage for my hand controls is 2.15V and I would like to know what is supposed to be. Looks like it is 1.89V for the 863F.

    Thanks,
    Steve