Bobcat 863F Lift Tilt Don't Work
I am posting this thread to try to get help from others, but also to help others who are searching for this same issue because I assume I will fix it and from all the reading I have done I will hopefully save others time by consolidating some information here.
Searching google and/or this site brings up a lot of hits about lift/tilt problems with Bobcats. However, none of the other post's descriptions of the BICS indicators show the same indicators as I am seeing.
I have a 2001 Bobcat 863F with BICS and Advanced Hand Controls (AHS). The bobcat has a key, a manual hour meter (no codes).
The problem is that the lift/tilt functions do not always operate. Usually turning off/on the bobcat allows the lift/tilt to work again. Most recently I can't get the lift/tilt functions to work at all. The bobcat can drive around no problem once I push the override button, but lift/tilt do not work (and don't even try to work indicating electrical problem, not hydraulic problem).
The BICS indicator is showing the seat light blinking (the seat sensor is disconnected because it didn't fit right with the new seat I put in). This has never been a problem as I have always pushed the yellow seat override button below the key (I think that's what that button is called but could possibly be called the Press to Operate / Traction Control Override button).
The Seat Bar indicator is on. In many other threads this switch is the culprit to lift/tilt problems but in my case the light is always on when the bar is down.
The Valve indicator is off. This is the indicator that the lift / tilt functions do not work, but the service manual does not indicate why the light might stay off. When there is a problem the light is supposed to blink 1, 2 or 3 times, but it does not turn on at all.
The Traction indicator is on.
The Power indicator is on.
The service manual has a section on diagnosing the joysticks by looking at the LED indicators on the left joystick, but the indicators do not turn on. The indicators not turning on indicate that the joysticks are not being supplied power from the BICS controller (at least that's what I deduce from the service manual).
I have tried moving the joysticks around and then turning on the machine in case they weren't centered, but that has not solved the problem.
My question is, does anyone have any idea what could cause the Control Valve indicator on the BICS controller to not turn on? I can't find anything in the service manual or online that explains the cause of the light not turning on at all. The only thing I have come across that seems plausible is that pin 1 on the BICS controller has a bad connection from the hydraulic lock solenoid:
From the poster named "special tool" in another post:
Hydraulic lock solenoid supplies a ground only to bics at pin#1....(maybe
check chassis ground continuity here? oxidation????)
My next step will be to look at that wire, but I've read about a relay that apparently controls the control valve solenoid but I don't see anything on the wiring diagram.
Things I am not 100% sure of and may be throwing me off, ie. the problem may be the seat bar even though the BICS indicator is correct:
1. From my understanding, the bobcat should both not drive or lift/tilt if the park brake is set indicating that the park brake circuit is not the problem since the bobcat does drive.
2. The bobcat should both not drive or lift/tilt if the seat bar is not down or malfunctioning indicating that the seat bar switch is not the problem since the bobcat does drive.
Originally Posted by hlukeh
I had this same thing happen to a T190. Turned out to be the TILT ACTUATOR SOLENOID.
Thanks for the info. I didn't realize that the lift or tilt actuators could cause the same issue. I'll check those wires as well.
Originally Posted by NCPIPELINE
I found the problem. I slid the fuses in/out because they are somewhat oxidized/covered in some sort of grit and I figured that may be the problem. In the service manual Fuse 6 is listed as the AHC fuse but in the bobcat it does not say AHC, it says something else but I forget what exactly is says. As soon as I got that fuse to have a good connection the control "Valve" LED turned on on the BICS controller. After finding that problem and driving around for a while I cleaned up all the fuses. After cleaning all the fuses I started the bobcat, drove around and then tried to turn it off and it would not turn off.
Bobcat won't turn off.
Turn the key on, no change, turn off no change, turn to start, starter grinds, turn to off, bobcat keeps running.
I went back to the fuses and removed the BOSS fuse (Fuse 2) and the bobcat turned off. I then started the bobcat and drove it around and it works perfectly. I then put in the BOSS fuse, started the bobcat and then tried turning it off but it would not turn off. I'm not sure why the label says Boss since I don't think the bobcat has any BOSS capabilities since it doesn't have the digital display, but it looks like it's labeled BOSS because it feeds power to that instrument cluster.
The wiring diagram shows that the BOSS fuse supplies power to the Engine and Transmission warning light, the fuel gauge, hour meter, engine temperature gauge and voltmeter, so I'm not sure how it affects the bobcat turning off. I didn't think to check if those items were working after removing the fuse but I thought they were. I'll have to check once I'm back at the bobcat. Those things were working previously, and the bobcat was able to turn off so something else has changed but I don't see what else it could be.
I'm not sure what it is that turns off the bobcat when the key is turned off. Does anyone have any ideas?
Looking closer at the wiring schematic, the only thing I see that makes sense as to why the bobcat isn't shutting off when the key is turned off would be that the power relay isn't unlatching when the key is turned off.
It possibly makes sense that the instrument cluster gauges and hour meter are drawing just enough extra current to keep the power relay latched if the return spring were to be worn out. The bobcat has 5500 hours on it so I would think this could be a possibility.
I guess one way to test this theory would be to plug the BOSS (instrument cluster) fuse back in, start the bobcat and then turn the key to off. If the power relay was not unlatching then I could probably lightly tap it to get it to unlatch. Or I could let the bobcat keep running and see if it stalls because the fuel shutoff solenoid should have turned off. It's too bad I don't have the bobcat here to perform these tests.
The fuel shut off soleniod is most likley bad, they can fail either way.
Originally Posted by hlukeh
same symptoms here except no seat light since my machine was not built with a seat sensor.
1.all lights are on except the valve lock light.
2.my fuses look good and clean(the only fuses I know of are by the engine next to the timing belt)
3.I'm getting 9.5ohms from the valve lock solenoid.(I read it should be 11 but I'm guessing 9.5 is better?)
4.I've disconnected the hand controls as well as switched the harnesses around to exclude actuator issues.
5.there is a grounding wire which comes out of the wires that go to the aux hydraulics which was previously grounded to the "Shield" that holds the controls under the seat. But since I just installed a new "shield" which is painted, I decided to attach the ground with a bolt for which I freshly tapped threads into the main frame with the idea that it would be better.
(btw the copper in the wire is a bit dark and it was previously connected to a rusted bolt which I had to cut off to remove.)
6. I've also disconnected the auxiliary hydraulics cable from the harness under the cab to exclude possible wire shorting issues in the cable.
Just finished resealing control valve spools,hydraulic pump control spools and sleeves, as well as replaced the tilt actuator with a new one.
The main hydraulic filter as well as both inline hydraulic filters have also been replaced during this round of repairs.
Before this, the valve lock light would turn on except for when I tried to use tilt(use of tilt being the only cause of the light turning off)
since finishing the repairs, the valve lock light has not turned on at all.
the machine drives but doesn't tilt or lift.
I've gone over the wiring and it seems good.
as far as I can tell the only thing left to check are relays and two other solenoids on the control valve but I'm not sure how.
The machine is a 1998 863F with AHC controls, it has 2,464 hours
Last edited by Axel; 03-19-2015 at 06:34 PM.