All, First post here. Hopefully can get some help. Machine Info: CATERPILLAR 259D 2015 FTL05838 The Right Track on the CAT skid steer stopped moving a few days ago. It was throwing a (Right Drive Motor Speed Sensor #1 Abnormal Frequency, Pulse Width Code) This code was on for a few days prior to it stopping. Today we traced the wires from this sensor and found one wire in the second harness has been rubbed through exposing the wire which was causing the code. We tested the white and yellow wires, and as per the repair manual, they are reading 7V. (repair manual says should be 8V +-1V) We repaired this, and the code cleared. (no other codes present) Thought this would fix our problem, however the Right Drive Motor will still not turn. The left one turns fine. The motor is getting hydraulic fluid, but it seems to be locked up. I suspect the problem is with the Right Drive Motor itself since it is not giving any codes, and it wont move more than ½” forwards and back. Any thoughts?
Usually my first go to is to pull the speed sensor. If you see metal chunks on it chances are there's an internal motor issue. My second go to is to pull the flushing spool on the motor. From my experience the flushing spool is a common failure. It has a washer on either end and they eventually get pounded to pieces and jam up the spool. I believe Cat updated the spool design a year or 2 ago.
Removing the flushing spool can be a PITA and it will leak a lot of oil out so you'll need to put the plug back in right away if you don't want to make a mess. There are springs in there too so make sure you note how it comes out.
92U 3406, I'll do those two things tomorrow. We fixed the wiring, but did not pull the sensor itself. As far as leaking a lot of oil... I suspect the oil in the drive motor has not been changed ever as the middle Allen key bit still had all the original paint on it from 2015. Thats why im really thinking it could be an internal issue. I apologize, but where is the flushing spool on the drive motor?
The flushing spool is on the motor. Its under 2 raised plugs. It'll be hydraulic oil that leaks out, not the final drive oil. Definitely clean that area spotless. Any dirt that falls in will go straight into the motor. If that oil is 6 years old, I'd definitely go there first. Drain it out and see what comes out.
Perfect. Thank you so much for this! This piece of equipment is actually in Iraq at the moment, and we're trying to get it going because we need it for clearing snow on Thursday. (yes snow in Iraq. We're in the mtns looking for oil)
Thanks for the help! figured out that one of the bearing blew apart, and subsequently ruined some gears and teeth. Good news is, after this repair, there will be no codes, and the track will move again! Kind Regards!
I have the same problem, my right side moves a few inches forward and back, but it’s locked, my left moves but not as freely as it should. It’s almost like the brakes are on the right track. I have a 2018 259D machine. Could you please be more specific on location of the flushing spool? New to this machine and learning it as I go. Thank you.
Insufficient information I’m afraid. Please post a Serial Number for accurate information.
I appreciate your quick response and apologize for the vague question. I am new to this post and didn’t think a new thread was needed because this seems to be the same problem as already posted. Serial number CAT0259DJFTL17055. I purchased this from Ohio Fabrik through an auction and it would not move. I had a code for a blocked hydraulic line and it said to replace hydraulic filter. I did so. It showed the right motor speed sensor code so I checked the wiring and plugs as directed, they were fine, so I wound up changing the speed sensor. Since changing it is still locked where it won’t move but a few inches forward and back. Not sure if it is another problem or what. Appreciate any guidance you can give me. Thank you.
A sensor issue should not stop the machine from moving a much longer distance than the couple of inches that you are reporting. Have you drained the oil from the planetary assem bly associated with that side motor yet.? See the attached procedure. It would not surprise me at all if it was full of "glitter" or even some larger chunks. Do you still have a list of those Codes.? If so please post them up. BTW if you don't have the manual that this extract was taken from you really need to get a copy. I can give you links to get one if you like.
I started the machine this morning and it actually did go forward and reverse several feet before two codes popped up And the warning saying the drive had been disabled until the issues were fixed popped up across the screen. I lined up the plugs to drain and will do that tomorrow. I contacted Ohio cat to get the history on the machine and it turns out in 2020 The piston drive was replaced on the right side, the side I’m having issues with. I will let you know what the final drive looks like after I drain it. Here are the codes, E2688-8 and I believe the other one was 695. I also earlier had a E879 code which I replaced the filter and it has not come back up yet. Another note, when I move the machine forward or back, and it decides to stop, you can hear a high-pitched whining from the right side motor, and the tone lowers as it comes to a stop. It’s almost like a squeak from a brake being applied
You have to think a bit outside the box on this one. The drive problem and the plugged filter could be related. Why would an E879 Event for a plugged hydraulic filter pop up.? Well the answer to that is, provided that it was genuine, the filter was plugged with some type of particles. The key is to discover where those particles came from. I'll bet money that you threw the old filter away and never cut it open to inspect it, right.? If you did that's an important potential piece of evidence has gone missing. Based on that it may be the motor side of the drive with issues rather than the planetary set. However you still need to inspect the oil in the planetary, even if it is only to rule it out of the diagnosis. They are actually 2688-8 and E695. The E695 is a consequence of the 2688. E695 - "This event is an active only event (will not be logged). The event designates the unexpected motor speed detection control has been disabled due to a motor speed sensor circuit fault." Attached is a troubleshooting procedure for the 2688-8. When testing for continuity at Step 2 of the procedure my suggestion would be not to use the resistance scale of a multimeter, it could give potentially confusing results. Instead, unplug the connectors at both ends of the harness that you are testing. Then you require a 3A test light fed from Battery+. Connect that to one end of the wire and connect the other end of the same wire to machine frame ground. That way you are testing that the wire can pass a significant current rather than the miniscule current a DMM uses to test for "continuity". Note this text from the procedure - "If this diagnostic code is active, the ECM will keep the code active until a good signal is obtained . This means that the drive motors must be moved in order for the ECM to determine if the active code can be cleared."
I did save the hydraulic filter and opened it up. I separated the mesh from the cloth and found absolutely no visible signs of any metal or debris in the hydraulic fluid. Upon opening up the planetary plugs on the motor, I drained the oil, and there were very small, visible signs of metal and both plugs magnets had a small dome of very fine metal particles magnetized to them. Your thoughts?
What you describe for metal on the magnets is completely normal. Nothing I would be concerned about.
Do you recommend refilling the planetary with new oil and seeing what happens? It’s only wasting a few dollars if it has to be drained again… I’ll try that next. Could dirty oil in there keep the machine from moving? When I pulled the original speed sensor, it was clean, and there seemed to be no debris on it at all.
Putting new oil in there is not going to magically fix anything. If you want to rule out the final drive portion for sure then remove the snap ring holding the cover on and pull the cover out to inspect the internals of the final drive.
This should be your next step IMHO. Try putting the filter media in a vice and squeezing all the oil out of it, then inspect it again. Check out this VIDEO from 4:18 onwards for the procedure. Unless the plugged filter Event was bogus - but why would it be if you fitted a new filter and the Event went away.? Although you have to ask yourself how long has it gone away for.?.
I changed the oil before seeing your last post. After starting it up, it drives 12 to 15 feet forward and back before the brakes lock. The more I do it the shorter distance it goes. To the point where it will barely move a few inches forward or back. Each time it stops, I hear a wine. 2688–8 code came up again. I just print it out Nige’s test procedure and will be doing that next.
Have you checked the undercarriage for jammed up or seizing rollers? Sounds to me your issue is likely on the hydraulic side though.
I tend to agree with you. That’s why I put that out there about it moving and the hydraulic filter blockage code. It’s like it’s starving for fluid and as you drive it more there’s less fluid to move it. Any suggestions? That hydraulic code could have been old. I watched that video… Very interesting… And did the same thing to my filter and found nothing. However, the filter looked pretty new. I’m wondering if maybe it was changed and they just didn’t get rid of the code.
Still have the issue of the number 2 speed sensor. I’ll do the testing tomorrow… Got too late today to try.
You may not be aware but that sensor you replaced is one of two built into a common body. The fact that only one sensor is throwing a code points to a potential problem with the wiring carrying the #2 signal. If it was a power or ground problem then you would also have codes for 2687 (#1 speed sensor) in addition to the 2688 code.
You should be aware that it is possible to “cross connect” the speed sensor wiring in such a way that a Code indicating a problem on one of the RH speed sensors is actually a fault on the LH side of the machine. BEFORE you dive into the troubleshooting procedure I suggest that you should verify that the sensors are correctly connected to the machine harness using the wire numbers & colours indicated on the electrical schematic.
The only way to “get rid of the code” is by using Cat ET to erase it. It cannot be erased while it is active, only when it is logged. This means it was active at one time but it is inactive now. If you had an active Event for a plugged filter then there are only 2 possibilities. First that the plugged filter sensor activated a bogus Event (but if that was the case why did the Event clear as soon as you changed the filter?) or second that you actually did have a plugged filter and the Event was made inactive as a result of replacing the filter.
Correct, it is possible to mix up the left/right speed sensor harnesses under the cab. But doing this alone brings on undetected movement faults and jams the park brake on in the same manner as the OP's fault. Which is annoying. FYI I've even tried to swap the sensor wires around to make the ECM "think" the speed sensors are in the correct sides. I figured as long as I travel straight the ECM won't know any different... turns out it does.
@Chrisso - thanks for confirming what I always suspected. To the OP. The first thing you need to do is check wire colours/numbers to confirm that all the harness connectors for the speed sensors are hooked up correctly.
So yesterday I dug deep into it. I pulled the snap ring off the final drive, and looked at the planetary gears. They were in excellent shape. Pulled them out, and ran the machine. With no sprocket or track on it it’s still locked up. I pulled the drive motor out and a part and a small chunk of metal had gotten into the piston drive and worn a groove in the Plate allowing fluid to bypass. Not totally convinced this is why I had the issues with the sensor codes but I won’t know till I get the parts and put the motor back together. I’ll let you know what the outcome is. Thanks for all your help… This forum truly is a great place for information.
Attached the parts breakdown for the drive motor. You may be lucky but at the level you are looking generally no piece parts are available.
Woody55 have you fixed it yet? if so, what was the fix? it looks like I having the same issue, tomorrow I am star to checking on it
I was curious to what fixed this if anything as i'm having a similar issue.