I picked up a new to me CAT 277B with only 1,300 hours on it, but unfortunately aux hydraulics and 2-speed are not working. I’ve chased the aux hydraulic problem, and have found the following: Proportional switch is functional when testing duty cycle at ECM input, Pin # 53. Range from 50% at neutral to 20% and 80% when rolling the wheel forwards and backwards. I believe this confirms that the switch and wiring are sound. I confirmed continuity between A1 and A2 solenoids and ECM, pins 40 and 58. Believe wiring is sound between solenoids and ECM. With cab raised and key switched to ON, not running, I do not have any duty cycle signal at Pin 40 or 58 at ECM. I believe this confirms that ECM is toast…anything I might be missing? Any chance the machine needs to be running to get signal through the ECM from the proportional switch to the A1/2 solenoids? Thanks!
Running, and pilot enabled, would be my educated guess.
Make sure seat and door safety switches activated when testing
As mentioned above, yes, because the engine RPM signal is also an input into the ECM. Zero RPM, systems they no worky.....
Have you checked for power supply to ecm? Possible blown fuse. I would want someone with et to verify no communication or faults.
Yes, I’ve confirmed power to the ECM. I will re-check signal to solenoids with cab lowered, door shut, etc. Also of note, when I click the RH joystick trigger button (continuous flow, I think), I can hear the hydraulics cycling on and off intermittently…sometimes they stay activated and won’t turn off when re-clicking the trigger button, other times the trigger button doesn’t do anything at all.
No it ain't. It's just the actuation for the AUX. If you want continuous flow you have to press two push buttons one after the other. If you don't have an Operation & Maintenance Manual already then you really need to make getting one a priority.
One more data point - pin #40 (A1 Solenoid output) at ECM has 9.1v power when machine is running. Duty cycle reads 88% when moving the thumb wheel, no change in any position. When the RH joystick trigger switch is activated the hydraulics audibly work (still intermittently) and the voltage changes to 9.5v, and the meter reads 61% duty cycle.
I agree with @Mobiltech . You really need someone with ET to ensure you have full communication and check for the presence of any Active Codes.
I’ll load it up and take it to the dealer Tuesday to see if they can read it.
If you do that have them download a Product Status Report (PSR) in pdf format before they mess with anything then another one when they finish up. That will give you a good idea what the situation is regarding the health of the machine.
Thanks, maybe they will think I know what I’m talking about!
If you ask them to do that it will demonstrate that you know more than most customers..........
And if they say "You want a what?" you're in the wrong place. Joe H
Alright, took it to the CAT dealer and they hooked it up to ET. The only thing definitive that the tech found was that the RH Joystick trigger button was throwing a low-voltage error. He didn’t see anything else that stood out. When I described the checking/testing that I had already done, he said it sure sounded like a problem with the ECM. I will note that he did not start the machine when hooked up to ET, only turned the key on. Oh, and I forgot to ask for the PSR!
That's all he needs to do. The Communication Adapter between the machine and his laptop needs machine power to fire it up. Do you mean the 2-speed trigger.? If so see the attachment.
It was on the Right joystick, which according to the schematic would be “work tool trigger” He did test the trigger button on the Left joystick and did not find any problem there. So even though the schematic I attached shows only two wires going to the work tool trigger, my machine has 3, I’ve also attached that pic.
Sorry, my bad. Wrong joystick. Can you ask what the Code was that he found.? Makes it easier to look up.
Trace the 3 wires back to the 12-pin connector. Does one of them (the orange one perchance) go into a pin on the joystick side that has no corresponding wire in the machine side of the connector.?
Thanks, I will open it back up Friday and see. I bought another 277B at an auction that just happens to be ~30 minutes outside of my travel route tomorrow, so I am going to pick that one up and see if swapping in the ECM from the new machine effects any change in the one I'm working on. If it does, then I know it's the ECM...assuming its that simple to swap them out and no dealer re-programming is required. Fingers crossed the new one has working aux hydraulics...
Just the fact that he could communicate with it is a good sign. The ecm in those only runs the aux hydraulics so the ecm cam be completely dead and the rest of the machine still works. It could still be a weak driver in the ecm though.
Aux hydraulics work in the new machine, going to try to find some time today or tomorrow to get the ECM's swapped.
You're lucky. You have a "known good" AUX ECM to use for testing.
Update: Swapped ECM’s and the aux hydraulics work. Looks like I need a new one! Anyone know a good source? eBay has a few, but not sure if they are to be trusted. The service manager at the CAT dealer I went to also told me that you must replace both ECM’s at the same time and that they require reprogramming…but based on being able to swap these ECM’s, is it safe to assume he is mistaken? Also want to note that he quoted $9,200 for the job!
How much did you pay for the 2nd machine? What's it worth with no aux hydraulics? Swap and sell, problem solved? Joe H
I think you can safely assume tha he's blowing smoket......... I see no reason why both ECMs should be replaced when only one is giving problems. The Interlock ECM does not have any separate software Part Number listed, so it is supplied pre-programmed. I'm guessing it will have a motherboard inside with a pre-programmed EPROM chip simply plugged into a slot in the board. That's how controls were back in the day. The Work Tool (AUX) ECM does have separate software listed. The P/N of an unprogrammed ECM is 216-0658. The software to go in it is a 284-3058. Alternatively you can get hold of what's known as an "Implement Service Group". The Part Number is 284-3059 and consists of the same ECM as above with pre-loaded software.
Thanks Nige, this is interesting...so the reason my swapped ECM worked is because it already had generic software loaded on it? If I purchased the unprogrammed ECM, it would not function? Thanks for the part numbers, that helps a ton.
Not a bad idea. I picked it up for $22k with 2,600 hours on it. OROPS, pretty basic, but runs good and looks decent.
It's not "generic". 284--3058 is the specific P/N of software to be loaded into the 216-0658 ECM for that application. The 284-3059 software appears to be standard for the Work Tool ECM on pretty much all B Series models. The 216-0658 Part Number of ECM is used on a much wider range of machines than just the Compact Equipment (SSL, CTL, MTL) Product Line. For example it is also extensively used (albeit with different software) in Backhoe Loader products. That is correct. It would not function without the appropriate software installed. The problem is that the ECM Part Number should be stamped on the outside, so anyone selling a used one will know what P/N it is simply by reading that number. The challenge comes in identifying EXACTLY what model of machine it was removed from and therefore what P/N of software is loaded into it.
Thanks Nige, I could have really been throwing money away had you not provided that insight. For anyone curious, I opened up the bad ECM and was surprised to see how clean everything looked:
The problem is that nobody in the dealership network knows how any ECM works internally, they just know how it’s supposed to interact with the rest of the machine electrical system. I would hazard a guess that only a few engineers in the E&E Dept at the factory have knowledge regarding the internal workings
There’s gotta be a schematic for the ECM somewhere out there…although I doubt CAT is very willing to give it away. I’m going to shoot them an e-mail anyway to see what they say.
I always wished there was a schematic available at the dealer level for all the ecm’s they use. I never saw anything in all my dealer years. I can think of many times I could have repaired an ecm with one fault instead of buying reman for an outrageous price. I have a few old ecm’s I keep around for testing purposes.
It will be classed as “proprietary information” and no way will they give it away. When downtime or dealer labour costs shed-loads of money to me it always seemed easier to throw a Reman ECM at it, flash it with the appropriate software, and have at it……