Gday gents. Have a CAT 825H wheel dozer/compactor. Won’t go into any forward or reverse gear. Going through the fault code trouble shooting on SIS has lead me to either replacing the monitor module, engine ecm or power train ecm. So that’s not ideal. It also has a speed sensor fault, but I wouldn’t imagine a speed sensor would stop it going into gear? Faults are; 0585 0248 0296 0174 0590 E0363 E0861 Any one experienced this? Cheers
Post a Serial Number please. Certain speed sensor faults could easily prevent the transmission from engaging gear. Your list of faults doesn’t make a lot of sense, they look incomplete to me, as in there should be a dash after (for example) 0585, followed by something like 07 or 09. Can you post photos of what you see on the operator monitor.? Three ECMs failing at the same time - unlikely unless you have been welding on the machine without disconnecting them. It’s more likely a communication fault or faults. Post some back story of how this current situation developed.
Hi mate. Yeh I only posted the CID number. It shows up on SIS fine. I’ll look for the full code soon when I go back out to it. I’ve checked the com link wires for continuity and shorts, all check out. Except when the monitor is connected, then I have 16ohm resistance to earth which I find strange. Bloke was operating it normal, then it just stopped on him. Couldn’t go forward or backward. Have new speed sensors coming, as I’ve tested them to definitely be open circuit.
S/n
That’s where your problem would appear to be in that case. If you disconnect the monitor and comms are restored for everything else then that points the finger. TBH when testing those CAN datalinks you really need an oscilloscope to be able to look at the waveform. The problem with the speed sensors could well be wiring-related. I don’t think I’ve ever seen multiple speed sensors go out at the same time unless something external such as welding or a lightning strike happened. A tip when testing wiring like that. Unplug both ends of the harness, connect one end of a particular wire to machine frame ground then use a 3-5A test light connected to batt+ and connect it to the other end of said wire. Sometimes multimeters can indicate continuity but a wire is breaking down under load.
Ah yep thanks. The only thing stopping me from changing that monitor is that it still seems to work fine. All warning lights work, park brake, oil press etc. According to sis the power train ecm uses both speed sensors and works out an adverage between the 2 . Maybe one had failed some time ago and it worked off the one good sensor. Will see what happens when the sensors arrive. The continuity to ground with the data link when the monitor is connected is still on my mind though. Will test it with a earth test light maybe like you mentioned
That is always possible. Generally in transmissions where the sensors are inaccessible and it uses two for redundancy if one is already failed then the 2nd one fails you're dead in the water.
Ahwell the speed sensors didn’t do it. Definitely a data fault with the power train module.
Update. Got ahold of cat ET. Only showing one active fault on there 672-1 (MID 081 - CID 0672 - FMI 01) Torque converter speed sensor fault. Tested the harness and sensor as per sis trouble shooting. All fine. (Sensor 1,000ohm) final step, replace power train ecm…. Still hesitant to order an ecm…
How many times did you do the test.? If everything pointed to the ECM being bad I would run it a second or even a third time to be sure. Heck I'd run it a dozen times.......... Also did you pull the main harness connectors for the powertrain ECM and take a look for the presence of green crusties.?
Heya Nige. Tested a heap of times. Checked every harness connector also. Another thing on my mind is, possibly a mechanical failure in the trans… As on the sis trouble shooting, it doesn’t say that this code will effect going into forward or reverse drive. My westrac mate says to replace the sensor even though it tested good so I will do that. Then I’ll dump the oil.
I'd be looking at the oil before dumping any more money on new sensors, but that's just me.