I have a 2003 Bobcat 763 with 160 hrs on it. A couple of weeks ago the seat bar relay apparently bit the dust. The machine would drive but the hydraulics wouldn't function. Sometimes it fixed itself, sometimes not. Dealer installed new relay and it worked fine for about 20 more hrs. Tonight the same thing happened. They said this was the first machine they seen with this problem. Anyone else have this problem? Kinda sounds like a short or something. :beatsme
Has the relay been bench tested to show it has actually failed? If not, it could be that an intermittent problem exists with one of the inputs to the relay in the form of a broken wire or dirty/loose contact. I can't remember ever having a relay fail in any application, it seems strange that 2 should fail in the same location.
First, let me clarify the problem as I wasn't running the machine when the problem started. While driving down the street the machine stopped solid and nothing would work, no steering, no hydraulics. Push the traction lock overide button and you could steer it. Forward to last night. Same thing happened. This was after the "fix". Anyway, sure enough the mechanic meets me at the shed and the Bobcat works perfect. He replaces the BICS sensor saying the plastic nut holding it down comes loose once in awhile and moisture may get in. Machine runs fine (it did anyway). I drive it around and use it for about 10 minutes with no problem. He loads up his tools while I start the Bobcat to put it back in the shed and it isn't working again! He messes with it for another 10 minutes checking all the wiring and says he's stumped. He is the best mechanic at the dealer so I've been told. Anyway he say's he want's to go back to the shop and have a look at some more manuals and talk it over with a few guys. He also wanted to see if something was heating up and causing the machine to operate after a cool down period like it seemed to do in the morning. That's where I stand right now. We will try again tomorrow afternoon. Still :beatsme
Just posting an update on the problem. The dealer found a short in the wiring harness. That explained the on again / off again problem. So far so good. Thanks.
badranman, i have the same problem with my bobcat 463. could you tell more about the short in the harness? where in the harness? how did they discover the short? thanks.
Man, you sure are blowing the dust off this thread, lol. I have no idea where the short was. If they did tell me, I've forgotten it by now. I wish I could help. Next time I'm at the dealer I could ask the shop manager if he remembers.
Thanks for the quick response. I did not look at the date when i responded to your "dusty" thread. I just did a search on yahoo and it brought up the forum. Let me know what you find out. Thanks again.
I have a 463. Look up to the left over your head after you put the bar down. The bar chaffs the harness here. Check this first.
A similar problem came up in the past week or so. I dont run Bobcats so bare with me. I will search the threads in a minute and update this. I believe the reply was to tilt the cab and check the wiring loom wherever it is cable tied. It seems that vibration causes a breakdown of the loom. check this.
special tool - Sounds like a good starting place. Thanks. If I don't see anything there, i will start at the fuse and chase the wiring through the relay, all the way to the solenoid. I will also look at the BICS circuitry too. Does anyone have a schematic?
It might be worth you checking out this one also.
I have the factory service manual. I can scan and post any diagram you need as long as my 3 year old daughter isn't busting my chops. Let me see if it has bics in it...
Thanks atlasrob. so you know,the traction lock light on the BICS flashes 3 times when the brakes lock up. The manual states this is a short to ground - which is consistent with everyone's chaffed wire theory. I'll check all of the suggested ROPS locations and wire tie locations and post my findings. It appears I will have to cut the mesh cover over the wiring harness to check the entire deal.
thanks tool. i can relate to the 3 year old ... i have a 16 year old that is running around here acting like a 3 year old! It takes forever to read and reply because he is so spastic. I cannot wait for his meds to kick in!!!!
Do you have the service manual, or the operator's manual? If you have the service, then you have the same diagrams that I do.
i have the operator's manual only. i've been looking on ebay to buy the service manual.
Okay. I have all the diagrams, but they are a pull-out, and won't fit in the scanner, of course - I don't know why they did that. Traction lock overide switch goes to pin# 22 and 12 on bics controller Seat bar sensor goes to pin# 15, 10 and 20 on bics controller Brake switch goes to pin# 23 and 4 on bics Hydraulic lock solenoid supplies a ground only to bics at pin#1....(maybe check chassis ground continuity here? oxidation????) Traction lock solenoid takes 12v (low)from pin# 3 (if happy) and sends it to the traction lock for a relay signal which opens through a 25a fuse from battery.
thanks for posting the wiring schematic info. i was not able to get to the garage today. it will likely be next weekend before i get back to troubleshooting the loader.
I have/am having the same sorta problem with my 763. A couple months ago I tried to get the machine going but the status LED wouldn't light up when the lap bar was down. I have a service manual, but my machine sits outdoors, and the temperature was about -40...too cold to fuss with mechanics. So I hauled it to the service/dealer, where it sat in their heated garage for a week-end before they got to it. The "problem" had disappeared, but they still inspected harness, etc. and found nothing. We figgered it might have been due to the rather chilly weather. But yesterday same thing happened and it was a balmy 30 degrees. So, it ain't the cold, because it has worked fine for the past 6 weeks in weather around 15-20 degrees. Like the rest of you, I'm stumped.
Not in to dusting as some!!! My 863 does same thing intermittently. Upon scientific analysis, it only does it when the BC parked and shut down on some kinda incline(not every incline every time), then upon restart she snags.Maybe mine is a relay/switch issue because i can usually get her back on track with a few raising/lowering of the seat bar....
Pretty much the same problem on a 863 C. I'm going to try all these ideas and at least chase down the wires.
A few things to check on BICS troubles...are the bolts tight where the seatbar pivots(can cause sensor to not see it is down) If brake doesn't release intermittent but all bics lights are on check the 1/4 inch bolt on the brake plunger...they can get grooves and hang up. also make sure to check for trash under or behind seat that will affect the seat sensor if it is old enough to have one
:notworthy Very good info, :drinkup and welcome aboard ( I see that is your first post, I hope you have more as good as that )
Yep, checked all those. Will keep u posted if she fixed or not....
These problems are not relay related. On the left hand side of the seat bar pivot point is a magnetic switch. It is incorporated into the pivot mechanism. This senses the position of the seat bar and opens and closes a switch using a magnetic switch. These switches run off a white plastic bushing with a brass insert and a magnet moulded into the plastic. They strip, wear out or otherwise move out of alignment. If your machine is almost new you may be able to remove the bolt and replace only the bushing. More likely you will need to cut off the nut (because the bolt will spin inside the bushing) and replace everything but the black switch mechanism itself. You can test the black switch part by watching the lights on your BICS controller (machine turned on not started) while slowly rotating the white bushing inside the black switch. When the magnet gets to a certain point the switch will close, and the BICS controller will indicate the seat bar is down. You dealer will stock the parts, they go all the time. I know for fact in the smaller machines (463 or S70) you can replace the switch without removing the bar from the machine, although you do need to disconnect the one side. I'm not sure on the bigger machines. Pete
Hey redneckpete, Thanks for that. Got her up on blocks at present so cannot check, but, if i disconnect the plug to that mag switch will it show up "error" on board or will it default to shut or open switch?????
Have you checked that the BICS solenoid valve on top of the BICS valve is working correctly? (not the spool lock solenoids, but you could check them too) When energized this valve supplies pilot pressure to the lock valves in the BICS valve which then open the oil paths to the Lift/Tilt cylinders. It has a screen on it which likes to collect metal filings, due to magnetism from the solenoid.
Thanks Crutch!!! Can you explain where the sol valve is(Bics valve)??? Bruce
The BICS valve is a casting that sits on top of the DCV. This is where the lines going to and from your cylinders hook up. It is used because the spool lock solenoids are not reliable/safe enough on their own. Here it is: Anybody looking for summer interns?
I'd be unbelievably surprised if that was his problem. The magnetic switches on the seat bar are KNOWN to be flaky and unreliable. The BICS system is all electric over hydraulic, the hydraulic side of which is highly reliable, and the electric side of which is pretty reliable. I'm off to a meeting tonight. I'll check tomorrow and pull out the manual for the troubleshooting procedure, but trust me, start with the seat bar switch. Pete
Good stuff guys!!!!!
bob cat seat bar sensor I am having the same problen with my seat bar sensor. I have taken it apart several times even used hose clamps to keep the magnet and sensor together so that I can operate the machine. only to find the very next day again, nothing works! The machine is a 2000 753 with hand controls. I am wondering if there is a way to by-pass the magnet and just hard wire the sensor? The machine does not have a seat sensor only the seat bar sensor> Thanks for any help. Rob
I am also having the same issue with my 2001 773. replaced the bar sensor and work for a little bit then out again. it will only move with the trac lock bypassed. has been running fine until now. i do have a repair manual for it. should i run down the wiring harness and check for bare spots? it only has 1400 hrs on it. Thanks.... This site is awsome by the way!
I forgot to add there is no codes being thown.
Rob, I'm kinda surprised on not having a seat sensor. Mines a '99 753 and has one. Don't forget to trace wiring all the way back to it's two sources - the fuses underneath the Hydraulic Oil Filter on the rear right, and the relays above the battery/below the Air Filters on the left. 'Tuck same may apply to you- but like I said, mines a 753...
I put the sensor in and it worked then didnt work. this thing is drivin me crazy. i checked the manual and it says the solenoid should have 8-10 ohms of resistance that unlocks the bic controller for the hydro's ( i hope) this one is steady at 11.6 ohms of resistance could this be my problem? Mine has no seat sensor... Thanks to anyone who can help...
When you lower the seatbar does the seatbar light come on in the dash???
It did come on... When i put the new sensor in it did but only worked for awhile like 15 minutes then quit. then next morning i went and took it off the seat bar and lined up the sensor and the magnet up and it came on but the holes didnt line up. so i put a bolt through it to hold it while i tried it out. turned it on ond of 5-6 times over an 15 minute period but not while it was running. worked good. so i took it out to use it and started diggin and grading boucing around nothing happed. then after 15-20 minutes i was backing up slowly and it clicked off. wouldnt come back or so i used the trac lock override to get it back across the street to work on it. took the sensor loose to move it around and nothing. so i started checking out the manual and it looks like it goes to the bics controller soleniod. so i unplugged it and check it with an ohm meter and it has 11.6 resistants. so i am stuck here again... thanks for the reply tho.....J
My guess would be that there is a loose wire somewhere between the sensor and the controller. Probably the 'easiest' way to troubleshoot would be to have the key on and seatbar light on, wiggle/move wires methodically from the sensor back through harness, checking to see when the light goes off. It may be a tedious process, but the dealer would probably follow a similar procedure, at shop rate. If the problem was the bics solenoid there would most likely be a code showing. Regardless of all other conditions, with the key on and seatbar down, the seatbar light should be on steady until the bar is lifted.
When it cools offf the bar will come back on until (it seems) it warms up. then off again. i dont even have to move the machine and after about 15-20 minutes it will go out again. tried again this morning and it came on until it wrmed up. i wouldn't a brok wire would do that?
Sounds strange, but then again it is computer controlled.... If it's not a wire or a loose connection, and the sensor is new, the next possibility is the controller, which on the G series is the main controller for the whole machine. This would be a very expensive part to replace, especially if it doesn't fix the problem. I'd wait for the light to go off ( when it should be on) and again wiggle/move the wiring and see if you can get it to come on. It is not unheard of for the wiring to have a poor crimp where the terminal is attached, inside the plastic connectors so wiggle those as well..
Just a thought outside of the box, but I'm wondering if the traction lock solenoid is going bad. Might explain why it kicks out when it gets warmed up.
My 1999 773 is acting up. Sounds like what has been described - light for seat bar is on sometimes, off sometimes and hydraulics follow the light, I'll check the wiring anything special about the 773 that I should know? Thanks in advance!
Yes it was the main controller... it cost 1200 to have fixed, but she runs great now. Thanks to all who tried to help.:drinkup
I have a 773 and lap bar sensor has been replaced. I have intermittent issue where machine will at its own will lock up and stop functioning. When this happens the Lap bar light is not on. At some point in the future it will for no apparent reason work again. I am no mechanic and know nothing about these machines. I own this machine and need it to function. I solved this issue. The lap bar light would not come back on so I First I took off the door near my left shin while sitting in the seat. Loosen 3 bolts at bottom take out one bolt at top. I removed the second loom of wires from the left at the top. The Lap Bar wires are in that loom. I disconnected the lap bar sensor and with the key off checked continuity on all three wires. I turned the key on and checked voltage on all the wires. 2 read about 2.4 volts one was ground. I then went to back of machine and opened the door. I disconnected the big round loom of wires. With a multi meter I verified with the key on that I was getting 12 volts on the center pin to ground. I connected that loom together again. There is a clamp that holds the loom to a bracket on the engine not too far from the connection. With the key still on and the lap bar still not functioning, I wiggled the wires that were wrapped together. The lap bar light came on and several warning lights went off at the same time. I removed the clamp and tried to separate the wires from one another. I saw no issues with broken wires but was no longer able to cause the problems. Each time I would turn the key off and back on. Prior to stripping the loom of its wrapping, each time I touched the loom the lap bar would go out, and other lights would come on and a beeping would occur. This would happen scientifically. After removing the shielding from the loom and separating the wires I was not able to get the problem to occur again. If I get another issue, I will go and examine those wires more closely. My guess is there is some issue in that spot but removing the wrap and moving all the wires around caused the wires to be in different places with one another. Machine worked flawlessly for hours. Yesterday and this morning it was inoperable. Problem has been persistent since I purchased machine used a little over a month ago. If you have a problem with the lap bar, with key on, go to back engine compartment and grab the loom where it is secured with clamps to the engine. See if lap bar comes on and other lights and alarms go off. My guess is the orange wire in the center is supposed to carry 12 volts to release lap bar and even though there appears to be no issue with the loom there is an issue inside it.