New guy here, and I want to first say thanks to those who provide this forum and also thanks in advance to those who are looking at my question. I am running a CAT HM312 forestry mulcher on a Cat 279C CTL. The mulcher uses the high flow system, which is currently working, but with a strange developing circumstance. In order to get the high flow circuit to come on, I need to raise the lift arms before rolling the right thumb wheel forward to power the mulcher drum. When I first started using the mulcher, I needed to lift the mulcher off the ground just a few inches in order to engage the high flow. Progressively, I have found that I need to keep increasing the mulcher height in order to enable high flow. I am now needing to raise the mulcher about 3.5 FEET to enable the high flow! Once I have the lift arms high enough to get the high flow to come on, I can engage the continuous flow, lower the mulcher back down, and the high flow stays engaged. Eventually, though, I am going to be at the top of the lift arm travel, which means no more high flow. I suspect an electrical problem here, but I have no idea what is actually in the high flow circuit. Any ideas what is going here? Thanks much!
You may as well post the machine serial number because the Cat guys will need it. I will tell you that info on a forestry machine may be limited here. I don't know if anyone can get access to that industry info.
Clarify... Does the mulcher activate in low flow, and, high flow isn't achieved until the loader arms are raised? If so, the harness is damaged between the connector on the loader arm and wherever it terminates in the mulcher. High flow requires continuity between two pins in the 14 pin connector. If those 2 pins aren't connected, only low flow will exist.
I'd bet the wiring on the loader arm is starting to go.and picking up the arms make the wire make contact to get it in to high flow
Right, then: the full number is *CAT0279CAMBT02484*. I probably should have also told you that the forestry mulcher has no wiring harness itself. To run the mulcher on high flow, I need to put a special jumper plug into the electrical connector on the CAT that ties the F and G pins together. Sorry for the oversights.
See Tyler’s suggestion above in that case.....
Yes, the mulcher will operate in low flow as long as I hold the right thumb wheel forward. However, it will also STAY in low flow if I simply hold the thumb wheel while raising the lift arms. To get into high flow, I need to raise the loader arms a bit and then try rolling the thumb wheel. If the high flow does not engage, I need to release the thumb wheel, raise the arms some more and try again. But once I get the high flow going I can lower the loader arms while holding the thumb wheel full forward and the high flow remains on right down to the ground. BTW, I should have noted that my machine has the 8 pin arrangement, if that makes any difference.
Definitely need to check the wiring from the 8 pin to the plug on the main harness also there is a continuous flow button on the left stick should be the lower left button. Also your machine has the early style final drives me sure to keep change the gear oil in then regularly if you don't already. That was a expensive life lesson.......
Well, that makes sense; I'll see if I can find anything tomorrow in the daylight. But what confuses me is how the high flow manages to STAY engaged, irregardless of the loader arm position, once I finally get it to come on. What is keeping it on?
Thanks, Nige. I will be checking the wiring tomorrow as Tyler suggested.
Once it is flowing oil the ecm may not need to see the signal from the jumper plug. This is just a guess I have no information to support this at this time. I can verify this with my 279c if turns out to be need be.
Thanks, Tyler. I will see if I can find anything in the wiring. Yes, I do have a continuous flow button and it is working properly. Regarding the gear oil in the final drives, I didn't know anything about that, so thanks for the warning. The machine has about 1400 hrs now, and I'm thinking the gear oil may be the original. Do I replace it with factory stuff, or is there something better?
Sounds reasonable to me! I wonder what would happen if I put the machine into continuous high flow and then had someone remove the jumper plug...
Yep factory oil is fine those finals are 5700 bucks each it pays to spend the 40 bucks ever engine oil change to keep them in good shape
Right, then! I'll get on that ASAP, too.
On the subjects of oils, do you have a manual.? The options are all listed in it plus a load of other stuff regarding basic maintenance and the intervals you should perform it. It can be downloaded in pdf from Cat for about $50.
Yes, I have the basic operating manual that comes with the machine. Somehow I missed or ignored the info on the final drives. But I see that CAT recommends their GO 75W-140 synthetic for my final drives, so I will pick some up today, I hope.
Well, it seems that I do have a broken wire that is making intermittent contact inside the harness that goes to the 8-pin connector on the left loader arm. The problem area is located in the rear, near the pivot pin for the loader arm, just before the harness heads down inside the rear structure. But before I cut the harness open to work on the wires, does anyone know of a more "professional" way to close the harness back up when I am done? Usually I would end up wrapping the exposed wire bundle with electrical tape, but I wouldn't mind trying something that looks a bit more upscale. What would they do if this harness was repaired at a dealership, for example? ALSO, it would appear that Tyler was correct in his explanation of how the high flow manages to stay engaged even with a broken wire: "Once it is flowing oil the ecm may not need to see the signal from the jumper plug." Yep, that's it! I put the mulcher into high flow, engaged the continuous function, then had the wife remove the jumper plug completely. The unit stayed in high flow regardless of loader arm position. And just to be certain that something else wasn't going on, I then tried to get the machine back into high flow WITHOUT the jumper plug: no joy. Thanks much for the help, folks.
Best you can do to fix the broke wire is a heat shrink butt connector then heat shrink over the whole works. Probably best the change the harness.
#6
Thanks, Tyler and Heymccall. Replacing the harness may be the best plan.
A potential temporary repair option for the existing harness would be to find which of the two wires in the harness for the High Flow ECM-to-ground signal is open circuit and run a new replacement wire outside the harness. Crimping a Deustch connector pins/socket on either end as appropriate would not be terribly difficult, and both ends of the wire could be instereted into the connector at each end of the harnes. Then cable tie the additional wire to the outside cover of the existing harness. A lot easier IMHO than cutting the harness open in an attempt to find & repair the broken wire because you first have to find out where in the length of the harness the break is.
Nige, thanks for the suggestion. I had wondered about doing that, but I don't know how to get the those Deustch pins/sockets to come out of their holes. (Truth is, I didn't even know what to call 'em!) Would I be correct in guessing that there are special tools to remove/install those wire ends? Do you have a preferred source to pick up these ends and the needed tools?
Google “Deutsch connector pin removal tool”. They are plastic and cheap as chips. There are videos on Youtube showing how the pins are removed from the connector body. The removal tools are quite fragile and easy to break if you are too heavy handed with them. The pins & sockets can be bought from the Cat dealer. Again they are not expensive, you would probably get a couple of each, male & female, for less than $5. I need to look up some part numbers but it will have to be later today.
Thanks much. Are they all the same standard size? I'll see what I can find out on the world wide web.
If you're never gonna use the 8pin for attachments, why not jumper the pins at the rear harness connection?
Or put a switch back there or in the cab to turn the hiflow on
I do use the 8-pin connector for other attachments. I have a CAT grader blade and an extendable tree shear with rotating head that both need electrical connections. Otherwise, though, the idea is brilliant: cheap, quick and effective! Likewise for Tyler's idea of a switch. Thanks, guys.
If you want something to repair a wiring harness that was fixed/spliced, opened up, etc, Ford has a special connectors and shrink tubing designed just for that. A good friend who's a Diesel tech. at a Ford dealer used it to repair the harness on my track loader. He also had some special tape to wrap the harness up but I don't think Ford uses it anymore. Cat may have something similar. A couple wires wore through and would arc. After I saw smoke and smelt burning plastic I had him take a look. Very bottom of the harness right by a keeper to hold the harness in place. He jiggled the jiggled the harness and found it. You couldn't feel it because it was under the keeper on the bottom. Some info below on the Ford splicing kits starting on page 2. 18376-Pigtail-Book-2016.pdf (motorcraft.com)
Dave Great reference work!
Just passing on what I've seen.