good day folks, I have a d4g serial number MHK3082 that will not move. machine was running great pushing up some rubble and suddenly locked up. Parking brake light came on with switch still in disengaged position. Toggled the switch with no change. Killed the engine. Upon restart I made sure the PB switch would only allow the machine to start in the engaged position. PB switch seems to be functioning properly. From there I went to the PB solenoid and cartridge. Solenoid is receiving its voltage signal and has a resistance of 10.8. I then removed the cartridge, it appears clean, and the plunger does shuttle freely. No signs of debris, damage, or any indication of sticking. Is there anyone that has some guidance on what my next step should be.
I think I would start by checking brake pressure
Just FYI that is the engine Serial Number. The tractor is WGB00917. I'm going to suggest a slightly different approach because initially it requires no special testing equipment other than a mulitmeter. The electronics that monitor the hystat drive system will cause the parking brake to apply if a signal is missing or corrupted. I would suggest to get into the electronics and look for Diagnostic Codes. It's very easy, only requiring a couple of pieces of bent wire. On the photo below are shown the locations of the Harness Code Plug #2 and the Diagnostic Indicator #4. You will find them just above the fuse box. With the key OFF unplug the two halves of the Harness Code Plug, then turn the key ON. The Diagnostic Indicator will start to flash. Use the attachment to decode what the flashes mean and post up your results. Be aware that that you have to scroll (aka increment) through the Blink Codes one by one because they do not scroll automatically. However before you do that I suggest that you check your electrical system voltage with the engine running. Experience has shown that the electronics on these tractors are affected by voltage, even something as mundane as an incorrectly tightened fan belt can cause all sorts of issues. So check that first. If the above throws up nothing then you are down to pressure testing. Hook a gauge up to the two circled test points one after another and test for pressure with the engine idling. If you have no pressure at either point then the flexible coupling between the engine and the drive pumps has failed. If it gets to that point there is a load of useful information contained in this THREAD , because to replace that coupling means the engine is coming out.
Thank you for the response however I must apologize and should had mentioned in my original post that there are no blink codes. CAT ET doesn’t show any codes either.
*CATOOD4GCTL X00937*
That would have been useful information to have earlier…… In that case jump straight to the last step of pressure testing.
Ah, so in your OP you mis-quoted the engine Serial Number as MHX3072 instead of MHX13072 which corresponds to the tractor S/N of TLX00837.
Thank you… I will get to that. When I was trying to troubleshoot originally, I didn’t have a pressure testing setup with me. I will post updates when possible.
In truth you only need one pressure gauge and do the test in two steps. You will require a 600psi gauge for both test points.
Ok sir, I’m finally back on here. There is zero pressure at the test ports.
That appears to confirm that the coupling has taken a dump. Engine out time - and before you ask there is no other way to do it due to space constraints. See attached. You don't necessarily need all the listed special tools, they just make it easier.
Thank you! Let the fun begin..