BACKGROUND: I have a Bobcat 863 that is in very good condition. Recently I had the timing belt replaced simply based on the hours on the machine (no problems). When I got the machine back from the shop, I noticed after an hour of use, that upon starting, lowering the seat bar, and pushing the green button that enables all features, the Traction Lock light would not come on. Here is the curious part: If the engine RPM is increased, the Traction Lock starts clicking in and out (you can hear the "clunk"). At full RPM, the Traction Lock will stay engaged "most of the time". At no time does the Traction Lock light blink to indicate that the BICS system detects a malfunction. HERE IS WHAT I'VE DONE: I checked the fuse and swapped the relay-- all OK. I checked the connector to the Traction Lock Solenoid (clean inside). I pulled the Traction Lock Solenoid and its clean and freely moving. I fully charged the battery and monitored its voltage as I run up the engine speed (around 14 at all engine speeds, battery voltage with the engine off is 12.5 volts). ANALYSIS: There is no abnormal vibration that might indicate that there is a loose connection somewhere. At full RPM, the Traction Solenoid is rather consistent in being energized when it should be. At a certain RPM it clicks in and out rather consistently, and at idle, it may sporadically click in for less than a second, but is engaged (Traction Lock unenergized) 99% of the time. SUPPOSITIONS: It acts like its a voltage-related issue somewhere in the system, but the system voltage is good and stable and swapping relays has no effect (so I don't think its the relay clicking in and out. The strong "clunk" of the solenoid doesn't sound like its shorted (thereby creating a weak magnetic field), and if it had an OPEN coil winding, then it wouldn't work at all. So, I'm at a loss to know what is going on. PLEASE: ANY IDEAS OR SUGGESTIONS?
Could be voltage related. Its two circuits. Pull and hold. If you alternator / battery voltage is dropping at idle you could possibly loose it there. Or possibly the hold circuit side is just getting weak and can no longer hold up the rod.
If you can't find a better explanation, check your grounds, all of them. or double them up and add more in more places, grounds are one place it doesn't hurt to have a cobbled up wiring system.
Delmer makes a good point. Had a few s series bobcats have issues at the panel due to issues in the harness/ grounds ect. I would flip the cab and back probe the plug on the parking brake solenoid and run the wires up through the side. Close the cab and hook up my volt meter to each side. Pull first and watch that voltage then change over to hold and operate machine as you described. See if your voltage is actually falling off when it locks or if your solenoid just cant physically hold anymore.
The solenoid "slams" into position with the same loud "clunk" that it always had. I did some more testing today. When the engine is at idle, the Traction Lock light is sometimes coming on (now) and staying on, but as soon as you rev up the engine to at 25% of my max RPM, the Traction Lock light goes out and then the Traction Lock solenoid starts cycling in and out (usually "in" for a second or less). Increasing the engine RPM up to 80%-Max results in the Traction Lock staying engaged. Voltages look good, but I am wondering about current capacity (a 12 volt lantern battery would be 12 volts, but would never start my Bobcat because it doesn't have the current capacity). Anyway, in poking around the internet, I came across a curious post from back in 2014 on a forum called Skidsteer.com. Here is that post: Re: Traction Lock Override on Bobcat 763 Posted: 10/01/2014 05:27 AM About 15 years ago or so I hired a 763 that was doing some grading for me that did the same thing. It started fine but we just couldn't get the darn thing to un-lock. I checked out the electrical circuits and each circuit was just fine, including the lock. Hauled it down to the dealer, some 70 miles away and he replaced the battery. Duh...... So, make sure you battery is putting out enough amps to kick the lock. The battery showed enough voltage but for some reason just didn't have the amps to kick the lock solenoid, even with the alternator running and charging. Strangest thing I've ever seen. I am wondering if there is any validity to this. What do you guys think? Perhaps I should pull the battery and get it tested. Might be that I have an internal short that isn't allowing it to supply enough current to hold the solenoid in unless it is getting a lot of help from the alternator (though that doesn't explain why it can at times hold at idle (but that is the exception).
If the machine is starting with no issue i would not suspect a battery to be at fault. You could always get it tested if you wanted to. The alternator could keep a surface charge only and the battery voltage would drain off once the machine sat idle for a period of time. If your not having issues starting the machine after it sat over night or a few days i personally would not suspect the battery as the cause
That's sort of what I thought, but then again, my machine has always started almost instantly (never had to crank, it is almost "instant on" when you turn the key). The battery is only 2 years old as well (wouldn't expect it to die that quickly, and the machine lives indoors in a heated space). Still, this seemed to cure the guy's problem in 2014. But that's why I was seeking opinions as to whether his case was some kind of fluke.
Ive replaced several of the solenoids over the years. Out of all the parking brake/ release issues ive had its been the solenoid 99% or the time. The coil/magnet on the hold site just starts to go and heat up loose its holding ability. Id lean more to it especially since your interlock does not have any other issues.
Just as a thought you could always remove the solenoid and pull out the plunger. Then run the machine. Of course you would have no parking brake but if you had no other bcis errors or issues that pretty much would zero you in.
The coil getting hot makes a lot of sense, as much as anything anyway. I've heard of bad batteries causing issues like this. I don't understand it though. Without a record of the voltages as this was happening, maybe an oscilloscope, or something more definite, I'm still suspicious it isn't something like a bad ground, or bad connection that gets knocked around with the battery change. There are issues like start solenoids cutting out that are easier to trace to not enough amps to the solenoid (too small/long wire) and the solution is to add another relay to switch the solenoid, so the small wiring is carrying only the switching current. You could measure the voltage at your solenoid when it's acting up, or wire in another relay temporarily to test it with a bigger wire supplying the power. There's just no such thing as having enough voltage but not enough current, UNDER LOAD, not enough current and the voltage will be low too. (reading without load can give you a good voltage that drops under load). It seems your voltage measurements are at the battery so far? try measuring at the failure point. Possible the alternator is weak, requiring more amps to excite at higher rpm, and that's drawing down the voltage in part of the harness away from the battery.
Good suggestions. I considered disabling the parking brake, but I live in the mountains of North Georgia and were the machine to stop (quit) for some reason on a hill, I'd be in a world of trouble without the Traction Lock. For what its worth, yesterday I pulled out the relay just below the seat front, and replaced it with a manual switch on the two contact connector points and put in a 100 ohm resistor in place of the relay coil at its connector points so that the computer wouldn’t see an open relay coil (coil resistance is 90 ohms). That was a total failure. Somehow the computer could see that I was fooling it and it threw codes (I didn't bother checking what codes they were because it was clear that I wasn't fooling it). The point of that exercise was to see if I could just make a "manual parking brake". I'm sure there is a way to do that, but what I did apparently wasn't IT. I wish I had a good schematic for the Traction Lock circuit. The Service Manual that I have for the 863 is pretty useless when it comes to schematic details (lack of reproduction quality, cut-up diagrams with missing information along the edges of the scanned pages, missing information, hard to follow). So, I guess the next step is to find the right relay coil on Amazon.com and do a swap-out. I don't have any specs on the coil resistance or magnetic properties of the coil to test the one in the machine. All I know is that it works under certain circumstances. When the engine is revved up, the alternator is putting out about 14.6 volts (as I recall from my tests 2 days ago). I think if it were malfunctioning it would be at a lower voltage than that. I could also use jumper cables to connect my truck battery to the Bobcat battery in parallel and see if there is any difference. Were the Bobcat battery to be too weak, I would think that the truck battery in parallel would overcome any drawdown of the Bobcat battery. Were that to work at all RPMs, then that might indeed point to the battery. If the problem is in the computer or cabling, that is a more difficult thing to track down. Since I just had the timing belt changed out, I tried to think of ways THAT could have resulted in this, but they didn't have to pull the Deutz engine to do that, so other than this coming on the heels of the timing belt change, I don’t see any association with thet other than this strange behavior occurred about an hour (run time) after that was done.
You're still talking about battery voltage right? I'm talking about the voltage that the coil sees. I'd run some jumpers to the cab and hook up a multimeter and see what the coil sees.
I wouldn't run it with out the parking brake for anything other than diagnostic purposes. Creating a new circuit for the solenoid would do anything for you if the solenoid it self was at fault. Its electrically released spring applied. You could give it voltage from another source and still loose the pull or hold. The solenoid has to hold the parking brake pin up and hold it against spring pressure and it does that in a vertical position to boot.. Back probe the solenoid and check with your volt meter while your working the machine. See if you maintain you hold voltage first. I always find it best to keep it simple when doing electrical diagnostic. Start with the most logical failure and work back. Your solenoid has probably been cycled thousands of times during its life. Its just my opinion but it start there
Gentlemen: I pulled the Traction Lock coil today and measured its windings. It is a Bobcat/Ingersol Rand Part No. 6667992 and has three wires: Red ( R ), Yellow ( Y ), and Black ( B ). The relative resistances of the windings are: R - Y = 11.0 ohms R -B = 10.8 ohms Y -B = 0.50 ohms There is no conduction from the metal case to any of the wires. Does anyone know what the winding resistances should be? or what the winding configuration is supposed to be? Txhayseed said, "Its two circuits. Pull and hold." So I would imagine that R-Y is one circuit (maybe hold) and Y-B is another circuit (maybe pull-in). The 0.5 ohm value for Y-B seems awful low (practically a dead short), so that could be a problem... but I don't know what's supposed to be inside the coil. Again, does anyone know what the coil configuration is supposed to be and/or what the coil resistances should be for a good coil? Thanks.
I would look at the engine rpm sensor at this point. "the faster the engine turns the higher the output ac voltage it puts out. The clearance betqween sensor and flywheel should be checked. On a t190 it is .050". The lower voltage may be tripping out the bics intermittently although not sure about it automatically resetting the traction lock.
UPDATE: (in my previous thread, I identified a Yellow ( Y ) wire... actually it is White (W)... just discolored). So, I ordered a replacement Traction Lock Solenoid and installed it. That made a difference. Instead of the solenoid not pulling in at idle and pulling in intermittently at moderate RPMs and engaging most of the time at full throttle, the Traction Lock now pulls in at idle (consistently), drops out momentarily at moderate RPMs, and engages 99% of the time at full throttle with bad results if moving at full speed (6 mph) at full throttle should it "hiccup" momentarily (machine jerks to an instant stop-- gotta be bad for the transmission). So the swap out of the Traction Lock solenoid coil had a positive effect, but did not address the underlying problem. Things to note: I measured the resistance between the three leads on the solenoid and found that they are identical to those of the original solenoid, so I can only imagine that the magnetic field generated by the old one was marginal, however there is still a momentary total drop out of the control voltage. The likelihood of this drop out is engine RPM-related. No error codes are generated when this happens. To the BICS, it is as if the seat bar were momentarily raised (for a fraction of a second). The Traction Lock light on the panel goes out and comes back on, BUT the seat bar indicator remains lit at ALL TIMES except, of course, when I manually raise it-- so as far as the BICS is concerned, the "seat bar down" signal from its magnetic sensor is continuous. This leads me to suspect that either there is a computer failure (unlikely because nothing else glitches) or there is an interruption to the Traction Lock Solenoid voltage at some place in the system that is NOT DETECTABLE by the BICS. Why things would improve drastically with the swap out of the Traction Lock Solenoid makes no sense. Were the original one bad, then everything should be working perfectly. Also, the vibration levels at midrange RPM are not very different from the vibration levels at idol or full RPM, so it is probably not a chaffed wire vibrating, but more likely a voltage related thing-- but having said that, if the voltage ramps up (due to increased alternator speed) form idol to max RPM, why would the intermittent behavior manifest itself at a mid range RPM? Can anyone explain to me the sequence of events for the energization of the Traction Lock Solenoid? From what Txhayseed seed said above, it would appear that there are perhaps two coils in the Traction Lock Solenoid, two to pull the solenoid out of lock (strong force, more current applied) and once the locking pin is retracted, only one coil is energized continuously to hold it in its disengaged position. That might explain why the Traction Lock Solenoid has three wires (two coils and a common ground). By Bobcat convention, black wires seem to be Ground. So perhaps the low resistance White-to-Black pair would be a high current (low impedance, 0.50 ohm) pull-in field momentarily drawing 26 amps, and the Red-to-Black (higher impedance, 10.8 ohm) pair is a lower current holding field that only draws about 1.2 amps. Does this sound reasonable. Does anyone out there know how it works (the sequence of events, which wires are energize when)?
Attached is an Electrical Schematic for an 863. The other things you may want to check are: 1. The switch on the parking brake pedal 2. The schematic shows a ground connection (black wire) on the chassis side of the harness that connects to the solenoid.
Dear Lowe.Buuck, your attachment is EXACTLY what I was looking for. No more guessing. I can clearly see what is SUPPOSED to be going on. My 863 does not have a Manual Brake Switch going into the BICS, but until I can find the intermittent cable connector or cable (which I think is more likely than a BICS failure since no error codes are thrown and the Traction Brake Lock light is correctly indicating when the Lock in engaged or not), I am thinking about adding a Manual Brake Switch that applies the pull-in current (momentarily) and then the hold current (continuously until manually disengaged) in a bypass of the BICS. That may make the BICS then throw an error code, but it will allow me to move the machine out of my garage in an emergency, because the ceiling height to too low to allow me to raise the cab to get to anything. I was fortunate to have the current failure to be an intermittent one correlated to engine RPM for some reason. At first, I could not disengage the lock at all, but when I discovered that I could ramp up the engine RPM and the Traction Lock would periodically engage, I was able to incrementally creep the machine out of the garage where I could raise the cab to inspect and service things. A manual override would let me pull the Traction Lock so the machine could be moved. I have read elsewhere that some people have trouble raising and lower their boom/bucket when a Traction Lock code is generated. Were that to be the caee, I might also have to "fool" the BICS by making it see a dummy traction Lock coil (e.g., the old one that I just replaced). I am hoping that my 863 does not associate the tilt/lift system with the Traction Lock in any way.
The brake switch is attached to the small Parking Brake Pedal on top of the chain case. I.E. Between your feet when sitting in the loader. Are you saying the newer model loaders don't have a Parking Brake Pedal? As for the ground, follow the black wire at the Parking Brake Solenoid back until you find that ground connection and make sure it is clean and tight.
Yes, my loader (S/N 51444xxxx) has hand controls (not foot controls) and no parking break. The Traction Lock is automatic. You get in, pull down the bar (the bar light comes on), you push the green start button and all the other lights come on (including [supposedly] the Traction Lock light). That light blinks out momentarily and you can hear the lock drop out and then instantly re-engage unless you are at a moderately low RPM when it doesn't re-engage. There is no manual parking brake (hand or foot actuated).
You probably want this schematic. It is for an 863 with Advanced Hand Controls, without BOSS.
If your battery starts the bobcat, it's plenty strong enough for a small solenoid. Check lead resistance back from controller to solenoid, make sure the pins at the connector are tight in their female counter parts.
According to schematic R-B= 10- 11 ohms W-B=.4 - .5 ohms R-W= sum of both coils in series between 10.4 11.5 ohms. Your readings looks good so far.
Sounds like your battery voltage is a little low. Should be nominally12.75 volts static and charge voltage should be 14.5 . Don't know if this is enough to trigger ;your problem or not. How old is this bobcat? The controller could be causing these issues especially if it has more than 5 years on it. Thats how long my new one lasted.
OK, problem SOLVED ! As Paul Harvey would say, "now for the rest of the story"... In my original post I started out with the background leading up to the problem. Repeating that here, I wrote: " BACKGROUND: I have a Bobcat 863 that is in very good condition. Recently I had the timing belt replaced simply based on the hours on the machine (no problems). When I got the machine back from the shop, I noticed after an hour of use, that upon starting, lowering the seat bar, and pushing the green button that enables all features, the Traction Lock light would not come on. " Having replaced the traction solenoid with little effect, I noted that the intermittent behavior was intermittent at low RPM, got much worse at a mid-range RPM, and then became infrequent at max RPM. That seemed to indicate a vibrational issue that could point to a bad ground. So I started tracing grounds. On the Bobcat 863, all of the grounds are joined together at one point on the negative battery terminal. When I got back to the terminal, I found that when I had the timing belt replaced by a Deutz machine shop, they had removed the ground terminal from the battery (I guess to be sure that nothing could be shorted out during the timing belt replacement procedure which was carried out without removing the engine from the Bobcat. They then replaced the negative terminal onto the batter post BUT NEVER RETIGHTENED THE BOLT HOLDING IT IN PLACE. So it looked normal, but it was not tight. You could easily lift the terminal off the battery post with two fingers! So obviously due to the mechanic's error in not completing his job, the terminal was loose on the battery post which, when resonant frequencies were encountered as the engine spooled up from idle to max RPM, caused the terminal to experience a poor connection. It apparently wasn't a total disconnect, but was enough to limit current, resulting in a voltage drop that didn't kill the computer and dashboard lights, but was insufficient to keep the traction lock solenoid engaged at all times. So the traction lock solenoid would drop out for a fraction of second at some RPMs and would totally drop out at others. So there you go. Problem solved (and thanks for the comments and help leading up to this point. Special thanks for the schematic of the traction lock system-- that was better than the documentation that I had).