So I have a gray market CAT 308C SR with parallel off set boom (Ser# CAT0308CPCRW01574) Started it up, drove about 200 yds and when I got to where I was going the boom, stick, and parallel off set boom were inop. I’ve searched all over for a broken ground, and cleaned grounds with no change. I started testing solenoids to see if I had some without power and found that the voltages at the solenoids under the cab were all over the place, anywhere from 4-21v. Also found some solenoids at the main hydraulic block with no voltage at all. Trying to determine if this is normal, or what I am missing here? Also, if anyone can decipher the CAT hose labeling for me, that would help significantly. (L1-4, R1-4, P) Pics attached. Thanks!
See the attached. I know the article is listed for a larger machine but the convention right throughout the excavator prodiuct line is always the same. Basically the three 308C models (KCX, CRW, & CPE prefix) appear to be pretty much identical with the exception of the swing boom on the CRW machine that you have. Therefore although parts may be different (see below) service information for the KCX/CPE machines should be broadly applicable to your excavator. I'll send you an electrical schematic for a KCX machine that might help you tracing missing power. Despite the fact that there is nothing online regarding parts information for a CRW-prefix machine there is a Parts Manaual available through the Cat literature system. The Cat Publication reference is XEBP8534 and covers all CRW-prefix machines with S/N above 1200, which includes yours. The closest parallel I can find between a CRW machine and the other two models is in the Operation & Maintenance Manuals. They're not much use to you because they are only available in Japanese..... However the same Publication Number XJBU2617 is for CRW machines from 1-837 and CPE machines from 1-1234. A different Publication Number XJBU2228 is for CRW838-Up and CPE1235-Up.
Thanks Nige, those are both super helpful. I was having a hard time cross referencing the domestic equivalent machine, so thank you. Still scratching my head about my varying voltage across the system. The voltage at the pictured hydraulic solenoids vary from 4v-21v. One of the solenoids at the pilot oil manifold shows 21v, the other shows 0v. I've been cleaning grounds everywhere I can find them, but they all show almost no impedence. Just feels like a bad ground to me.
I think you might be right about the grounds. The schematic should have all the grounds shown with links to their location on the machine.
Thinking a bit more about it, try disconnecting all the solenoids bar one. Doesn't matter which. Then measure the voltage to it and repeat for all the others with just one solenoid connected at a time. Report your results. It looks as though all those solenoids share a common ground in the brown wire. Question: Is there a Part Number stamped on the manifold where the solenoids are mounted.?
Thats a good idea to test individually. I am also going to pull the batteries and have them load tested. The machine is on a job, luckily I had just finished when it went down. I was able to get the bucket chained up off the ground and will move it home Thursday. I'll resume troubleshooting then and get some part numbers for you. Thanks so much for your help! As a small business owner in CA there is no way I can afford to pay to repair stuff. Most things I can get figured out myself, but help from people like you literally keeps me in business.
Hey there - New guy here. This forum and thread just popped up on my google alerts. I have a similar machine (2002 308CSR) /CRW prefix. I am not a mechanic, but have had all the same problems as you have described above. Fortunately, a very knowledgeable Cat mechanic that i used to know talked me through diagnosing and fixing these issues over the phone. Unfortunately, he is no longer in business. Way too much info for me to put down in a thread at the moment, and my machine is in a remote location right now, but if you want to DM me, I can probably help you out if you are not in too much of a hurry.
DM sent…thanks
Could you perhaps convince him to register on the forum and contribute regarding this issue.? There are a number of people who would be most appreciative, not least a couple of owners with problems.
I did register on the forum earlier in order to reply to this thread. I am very legit, and if Shane chooses to call me later, that will be that, and he can post comments here later. Just offering to help because I have, in years passed, wasted way, way too many hours trying to figure out what the heck was wrong with my machine. I am a slow typer, and just can't dump a bunch of detailed info about these issues, unless i spent the next two hours typing it. Don't have the time for that. My machine is in a remote location atm (not near me), but can contribute additional info and pics the next time I am at the machine. Just here to help out guys. No hidden agenda.
Well great news, its fixed! Huge thanks to Nige and Crawler1 for their help, suggestions, and knowledge. Would not have been able to figure it out without them. So heres what I learned. There was a Japanese only option known as an "Arm Crane". It came with a shackle at the end of the dipper stick, as well as several safety provisions. These safety provisions required sensors on all the arm cylinders to detect overloads. If there was an overload condition, those cylinders would be locked out to prevent tipping the machine etc. These systems go haywire for a few reasons. Could be a bad alternator, could be bad batteries, theres multiple sensors in the system as well as a couple of solid state wizbang computers. Identifying whether or not you have the system is fairly straightforward. First indicator is a small monitor mounted in front of the right side control stick in the cab. Second indicator is an aluminum placard opposite the VIN tag in the boom well. Then theres the shackle mount on the dipper approximately 4" above the bucket hinge pin, as well as electrical sensors on all of the cylinders on the arm. In working order you'll also notice that any time the bucket gets close to the cab there's an audible beeping. See pics attached for identifying if you have this system.
Underneath the cab is a pilot hydraulics manifold. There are seven solenoids all in a row, along with one hydraulic tank return line (see pic in first post). These are the solenoids that shut down the arm functions once an overload is detected. The simplest solution to fix this issue is to simply bypass this manifold block. To do so you will need 7 #6 seal-lok couplers, to connect the seven circuits together directly, and one #6 seal-lok plug, to plug the tank return line. You'll want to plug the return line first, otherwise it will siphon out of the hydraulic tank and you'll loose A LOT of fluid....ask me how I know....
Unfortunately this doesn't really fix whats wrong, it only bypasses the malfunctioning system. Normally I wouldn't go this route, but since there's no manuals available for this system in english, the monitor was all in Japanese, and I really didn't have much use for it anyway, this was the most practical solution. In the long run I will likely take the time to ring out wires and remove as much of this system as I can to clean things up, I don't care much for loose ends. Other potential solutions could be to run keyed 24v to all 7 of those solenoids, keeping them open all the time. Or if you're really savvy maybe you could figure out whats gone wrong, but without a wiring diagram and troubleshooting guide, that was a bit beyond my abilities. All in I was about $40 in bits and pieces to bypass everything and the machine works great. I haven't seen any creep in any of the functions at all, and no other symptoms to report. I know there's been a few people scratching their head over this one in the past, so hopefully this helps somebody out.
Awesome work! Love to see folks collaborate and make things work. Thanks for the detailed follow-up.
Okay, new development. I got a chance to run the machine for a few minutes and realized that with my bypass solution any time I boom up, the dipper moves out. That’s not going to work. I’ve attempted to trace the pilot lines and can’t find anywhere those two functions interact. No idea what would be causing that. In considering an electronic bypass rather than hydraulic, I hooked one function back up to the manifold block, ran 24v direct to the solenoid, and it worked. I then ran the part number off the solenoid to confirm that they were simple on off, and unfortunately they are not. They are proportional solenoids. So I suspect, based off the voltages to the solenoids from the machine being all over the place that the computer either has a bad ground, or has gone bad internally. I’ll check the ground later today. My question at the moment is, does anyone know if I can just run 24v to these solenoids permanently? Or will that burn them up? Or is there some other reason I can’t run them wide open? Not my first choice since that wasn’t the way it was designed, but trying to explore options. They are CAT part number 111-9916. Thanks in advance.
If you loosen the locknut on the end of the solenoid and wind in the screw it will manually open the valve as if there is power to it I've done this on a Japanese "shovel crane" Cat 320D that had the wrong Implement ECM or something like that but that only had 3 solenoids in the bank (boom up, stick out and bucket open)
That’s good to know. I didn’t realize they would go full open like that. So I went ahead and wired 24v direct to those solenoids just to try it, but it provided the same results. All the functions work, but when I boom up the stick moves out. Seems highly unlikely that two things went wrong at once, but I can’t figure how those two are connected.
So in my continuing effort to troubleshoot I tried moving the pattern selector through all of its positions, and the problem stayed with the functions. I had expected the problem to stay with the control inputs since I had been working on the pilot controls, but no matter which position the pattern selector was in, every time I boom up, the dipper moves out. Very open to suggestions if anyone has any ideas…
Alright, I think we got it licked now. I can't say I'm entirely sure how or why, but everything is working properly. I went back and put everything the way it was originally, confirmed nothing was working, and then bypassed each solenoid one at a time starting with boom up. The big difference this time is that instead of removing and plugging that return line, I left it on the manifold and used actual caps to cap off the manifold connections after removing the hoses. I did boom up first without doing anything else, and it worked without the dipper moving. Then moved on to boom down, dipper out, dipper in, then the parrallel offset boom circuits one at a time, testing each one. There is one additional valve in the middle of the manifold that is unmarked. Since everything was working at this point I left it plugged in, with the solenoid unplugged. No idea what that one is for, but everything is working so I'm not touching it. The only thing I can figure is that there is some sensor, or another hose on that manifold somehwere I can't see that needs to be pressurized. Who knows. Once again, hope this helps someone else out. Huge thanks to crawler1 who took the time to send me some more info from his machine that got the same treatment.