I have had a few intermittent problems with my lift and tilt functions locking up at random times. The BICS Control Valve light flashes three times (grounded circuit) when this occurs. I have been completely through the wiring harnesses. I am now thinking the control vavle sensor is the next likely culprit. But where/what does the BICS monitor for the control vavle circuit. Is this the Hydraulic Lock Solenoid? If I key off the tractor and restart the error resets. The BICS was randomly locking up both the control vavle and the traction lock. With two separate errors I suspected a chaffing of the wiring harness. I went through every inch and the wire is in great shape. After some reading on a couple of forums I replaced the traction lock solenoid. That seemed to fix that part of the problem - although my testing only involved driving it across the parking area. The old traction lock solenoid measured 0.35 ohms and 12.3 ohms - just outside recomendations. The new solenoid measured 0.37 ohms and 11.2 ohms. Still just outside but closer to spec... I measured the hydraulic lock solenoid but it has been a week and I do not recall the numbers. I recall that it measured within tolerance. Any other suggestions to look for on the control vavle error? Thanks in advance for your help. -dch
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You mention that the error code is for grounded circuit, i wonder if the control block lockout solenoid may be shorting out internally. It sits on a stem on the control block, i have seen them fail on the inside where it sits on the steel stem and shorts out. It could be your problem. The BICS box doesn't have a sensor, it just knows what the resistance/voltage to the coil should be, if its out of spec it will show you an error.
My first suspect would be this coil.
My first suspect would be this coil.
Tazza, Thanks for the suggestions. This solenoid is the one on the side of the control block, not one of the two up on top? Out of town for a couple of weeks but that will be my next step. Thanks again.
Yes, the one that sitcks out the side is the one, the othr 2 that are on opposit ends are your aux control coils. You could try running 12v into the coil and see i fyou can hear the stem click, i did that when working on my 751.
It has been a while since I followed up on this thread. I replaced both solenoids as discussed before. The tractor seemed to be fine but it sat parked for several months. I finally moved it to my other property - about a one mile drive so I roaded it there. About 3/4 of the way the lockup occurred again. And then a second time before getting to my destination. The tractor gets used intermittently so I have managed to put off deeper digging. But this past week I was using it quite a bit and the lockup happened enough to be quite an annoyance. To recap, I physically went over the wiring harnes from the connector at the BICS controller to the two solenoids. This included removing all bulkhead grommets. I could not detect a crack, split, chafe, stretch, or any other type of wiring anomily. The crimp terminals were seated well in the connectors (although I did not eject the terminals and inspect the crimps). I physically removed the BICS controller board from its case and "eyeballed" it. I did not see any physical isses (burned areas, cracked board, loose components, bad solder joints). The wiring schematic from the service manual and the matching physical wiring loom for these two circuits seem pretty simple and straight forward. So with the solenoids replaced and the wiring comfortably called "good", isn't all that is left the BICS controller? I have not priced a new one, but I suspect there are lots of zeros at the end of the price... Does anyone ever see these come up on ebay / craigslist / or some other sale outlet? Or am I missing some other cause? Could low tire pressure and faded paint have an effect? Thanks again, Daen
You replaced the coil, but did you do the stem too? i wonder if its not fully seating and possibly being released... I really don't know...
When the fault occurs, can you check for voltage at the coil? if its lost, thats your problem, but if there is power it has to be the stem.
Worth checking?
Thanks much for the suggestion. Depending on the cost, might be cheaper to just get a new stem... It has been several months since I did the work on the solenoids so my memory is a little foggy, but I am nearly certain I did not replace the stem. Thanks again. Daen
The stems can be pulled apart too. It may be worth trying to clean it first, if it fails, then get a new one.
Hold the part with the O rings in a vice with allow blocks to prevent damage, then un-screw the upper part with a spanner, it should seperate pretty easily. Clean with solvent, blow down with compressed air, re-assemble the same it came apart.
If it fails, you have lost nothing but time.
I think I better get some clarification on what the stems are. I was thinking this was the shaft the brake interlock solenoid drives down. Are you refering to some stems on the valve body? Daen
The stem is the part the coil slides over. The magnetic field pulls a plunger up to allow oil to flow.
You mentioned that the hydraulics are being locked out, your park solenoid wouldn't cause it to not function.... It would make you stop in a hurry though.
I may be getting muddled up too.
Not too muddled... I have two symptoms that happen at the same time. When the "lockup" occurs the parking brake engages (and nearly throws you out of the cab) as well as the bucket and lift arm hydraulics freeze in the current position. If I look at the BICS controller it has lights flashing. To this point, the only way to reset things is to power off the key and then restart. Might happen again in a few minutes or not for a few days... I have the full service manual and have identified the stems. I think the book is calling them a solenoid cartrdge. So perhaps a flaky cartridge / stem escapes from the solenoid field which the BICS controller somehow senses as a fault and it throws the "ALL STOP" alarm... Again, haven't priced a cartridge, but I'll bet is is much cheaper than a BICS Controller! Would you replace one stem or both on the control valve. What about the parking brake. Anything "stem like" to replace there? It looks to me like just the plunger and the "T-bar" that engages the parking pauls. Thanks again. Daen
mrfixitpaul
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If you have the manual, you can look up the code that the bics controller is giving you...which light is flashing and how many times. I believe that if the bics senses a lift/tilt problem it won't automatically lock up the traction lock (brake). You may have a different problem than the solenoid/stem valve that you are leaning towards.
bobbie-g
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From what you describe, you have more going on than a stop-solenoid problem. However, let me recount that I did have a problem with the stop-solenoid on my 751 a couple of years ago. I found the foot switch ("parking brake switch?") was intermittent, and not releasing the solenoid when it should. I took it apart, cleaned it, reassembled it, and have never used it since. If that switch decided you meant to step on it, it would throw the solenoid into the toothed wheel and throw you out the front.
---RCHere is a little more information. I was using the tractor all day today backfilling a trench. Of course being busy with the task at hand, you never quite pay as much attention as you should... so my information is not complete. The park brake lockup happened a handful of times. Does not seem to be related to activity, ground speed, throttle position, being rough, being gentle, etc. A few posts back I discussed how the lockup affected the lift arms as well as the park brake. Well, it "did". But then I did the solenoid replacement some months back. Today when the lockup occurred I noted that the lift arm was not locked up. I cannot confirm it was not affected every time, but it would seem the liftarm issue was resolved with replacing the solenoids. Tomorrow I may change my story back again.... The thought that the parking brake switch might be intermittent would be something to investigate. However, I have tried engaging and disengaging the brake switch, along with pressing the override button. The keyoff / restart cycle is the only thing I have found that clears it. From a distant memory, the BICS controller is flashing three times. Whatever it is flashing, the sequence code was indicating shorting to ground. That is why I when through the original steps of tracing and examining the wiring harness looking for a bare section shorting to the chassis or other. I am pretty competent at wiring - I have built miles of wiring harnesses for flight simulators - so feel fairly confident the individual wires in the park brake circuit are sound. I really appreciate everyone's thoughts. Keep them coming. Now I have to solve another problem in the morning... When you are working "down hill" all day and the fuel low warning comes on, don't turn around and go "up hill"! So is it particularly troublesome to get air out of the system? Any words of wisdom. Have yet to even read the service manual on how. Right now I am satisfied reading the label on my Corona! Thanks again, Daen.From what you describe, you have more going on than a stop-solenoid problem. However, let me recount that I did have a problem with the stop-solenoid on my 751 a couple of years ago. I found the foot switch ("parking brake switch?") was intermittent, and not releasing the solenoid when it should. I took it apart, cleaned it, reassembled it, and have never used it since. If that switch decided you meant to step on it, it would throw the solenoid into the toothed wheel and throw you out the front.
bobbie-g
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Daen, great feedback on what you've found and what you're thinking! That's what makes the forum so valuable. I've found it's simple to recover from ingesting air after you run dry on diesel. Sometimes, I just crank for several seconds and it recovers on its own. The better way is to use the primer bulb in the fuel line just before the filter. There should be an air bleed screw on the top of your filter. I pump the primer bulb until it's not spongy, hold it tight, then open the screw and let the air out. Then I close the bleed screw before I release the primer bulb. I know the primer bulbs are supposed to have a check valve, I just ignore that fact. There is probably a second air bleed valve higher up, right at the inlet to either your lift pump or the injector pump (may have an internal lift pump). Same story with that one. Once you are squirting diesel out the upper bleed screw, you're ready to crank. I've heard horror stories about how hard it is to prime some diesels, but not on this forum. I betcha you won't have any trouble at all. ----- Next issue: the locking "brake" solenoid. You can disable that puppy by accessing the top of the chain case and physically pulling the solenoid up, then using a hose clamp to keep it in the withdrawn position. Not recommended (no brake at all now), but I've done it when mine was acting up. At least it allows you to move the machine to a shady work location.
---RCI had the lockup again this morning. I observed that the BICS controller is definitely flashing the traction light three times (hold coil shorted to ground). I tried to get it to lockup by bouncing up and down on the seat and giggling the connector at the BICS. Nothing. Talked with the service manager at the dealership. He agreed that there was not much else in the circuit but the solenoid, wiring, and controller. He noted that there had been a fair amount of trouble with connections at the BICS controller connector.Daen, great feedback on what you've found and what you're thinking! That's what makes the forum so valuable. I've found it's simple to recover from ingesting air after you run dry on diesel. Sometimes, I just crank for several seconds and it recovers on its own. The better way is to use the primer bulb in the fuel line just before the filter. There should be an air bleed screw on the top of your filter. I pump the primer bulb until it's not spongy, hold it tight, then open the screw and let the air out. Then I close the bleed screw before I release the primer bulb. I know the primer bulbs are supposed to have a check valve, I just ignore that fact. There is probably a second air bleed valve higher up, right at the inlet to either your lift pump or the injector pump (may have an internal lift pump). Same story with that one. Once you are squirting diesel out the upper bleed screw, you're ready to crank. I've heard horror stories about how hard it is to prime some diesels, but not on this forum. I betcha you won't have any trouble at all. ----- Next issue: the locking "brake" solenoid. You can disable that puppy by accessing the top of the chain case and physically pulling the solenoid up, then using a hose clamp to keep it in the withdrawn position. Not recommended (no brake at all now), but I've done it when mine was acting up. At least it allows you to move the machine to a shady work location.
I am also going to reexamine the brake switch cable very closely. The switch may be fine, but perhaps one of the wires has chafed.
A new controller through the dealership was around $350. Not as bad as I had anticipated. It may come to that. Are there any parts dealers through the internet?
Daen
I have been absent this forum for way too long. I was reviewing my posts and noted I never gave the final resolution to this matter. After finding the issue all makes sense... but the path getting there was anything but direct. The short answer is that one of the mounting bosses on the alternator was broken. It was tight enough that the belt was turning it and generating power - but just barely. Since this tractor is only used intermittently AND the desert is torture on batteries the fact that I usually had to jump start was tedious but not unexpected. In a nut shell, the BICS would fault due to low voltage - either directly or because the low voltage caused erroneous sensor readings that instructed the BICS to fault. I replaced the alternator and have had zero issues since - including jump starting.
Excellent find, not sure i would have thought alternator with those errors, but it does make sense.
