Deere 872D Dash Panel on/ off and now dynamites the park brake

[Blue-Fox]

Hello all, my 2007 872D just started having a problem with the gage cluster - it seemed like the wiring might have been messed up in the column causing it to blink on / off here or there when you moved the rack in or out it could go blank then restart. The machine did not seem to be affected so we kept moving hoping to finish out the storm. Then it starts to dynamite the parking brake. Once grading, the next time roading in 7th gear, full lock up. So limped it to the shop. Checked out all the wiring from the unit all the way to the rear of the cab floor. There does not appear to be a wiring issue, other than one Deutche connector seemed to be sensitive and thought that was it. Gave it a once over push testing pins in each side of the plug and got the dash unit up and going for several hours while we re-wrapped all the wiring back into some new split loom. Pulled the dash unit and ran the wiring back into the column and installed the dash and NOTHING!!! Like it doesn't work at all now. Machine will start right up and run and all the lights work etc (just no gages)
Does anyone know if theres a "Computer scan tool" that will work on these graders without having to go direct to Deere? Or is that what we are stuck with?

 

[Blue-Fox]

SO I untaped all the looming and wraps and pulled the DC sets all apart and decided to flex test the complete individual wires going back several inches from the plug each way and no faults found. Took the connectors apart and checked out each of the pins and the sockets and the fit between the socket and the pins, just making sure each one feels snug, and each one felt like it had a good drag on/off of each pin so basically found no issues with the DC that I WOULD HAVE SWORE YESTERDAY WAS BUM..
I put section all back and got in the seat and cycle the key and now the unit would not work at all. Probably cycled the key 10 times. NOTHING. Messing around with the key more and trying to jog the column all over and even gave the dash a "FONZ" whack' - nothing.
Several minutes goes by as I'm just setting there in the seat and thinking back through this whole weekend and now probably another week long nightmare "where is my nearest match and gallon of gas?" Bam the panel blinks on and off. Couple more weak blinks. I never touched anything. It does it several more times and the gages even freak out and peg out and never even completely powers up but its trying. Then its dead. I push the hazards on (which had been dead a few times) and then something like a relay "CLICK" from back behind the seat and Bam the dash is fully operational again. I tried every thing short of a baseball bat to get it to fail and NOTHING can make it fail. Pulling on wiring and shaking it all over like I swaer I could jump rope with this harness and nothing is wrong with it.
Put tape back on wiring and looming all very cautiously put all back in the column a little bit at a time with unit powered on whole time and it's great. Get in the cab and do a ful function test, check diagnostics, check all the switch functions, check codes, check settings, the unit is perfect. Unplug the last plug to get the last piece of wiring back into the column and try to check out the machine and low and behold - its dead again.

 

[Pickawinna]

Could it be a relay playing up?
I have a 770D but havent yet had an electrical issue with it so I dont know any of the electrical system...yet.

 

[Blue-Fox]

Could it be a relay playing up?
I have a 770D but havent yet had an electrical issue with it so I dont know any of the electrical system...yet.

Thats been my suspicion, and so I pulled all the panels out from behind the seat to investigate. Its really strange because this thing has been rock solid running almost daily and all of a sudden now it's crazy. Other than dusty stuff here or there when you open up panels or wiring looms it's like a new machine.

 

[Pickawinna]

Why cant every machine just come with a full electrical diagram as standard alongside the operators manual.
I think you your best friend needs to be a multimeter. But I dare say you need to be looking further back. Even right back to the earths. Then figure out how the power is supplied from battery/alternator via ignition key ( that could be your problem area even) and then via relays etc. to the cab.
If it has been throwing itself into park as well then I dont think your fault will be in the dash cluster or cab wiring loom. Its further back. Thats my gut feeling anyway!
More than likely it is something simple.
But my point is start from the basics like battery connections-earths-main relaysi etc.

 

[Blue-Fox]

Thats where I always start anything electrical - the battery connections and cables and ground locations. So I found that if the trans fluid level indicates it is low while you are in motion it will apply the e-brake so there is another possibility besides the actual shifter having a short or other problem engaging the park brake.

Well got with the dealer today and found in a technical training manual that the CMU, (Canbus Monitor Unit) cluster is powered off of F28 10 amp fuse and found no issues there. I did learn there is a Multi Function unit over in the right side under the console that talks to the CMU and thinking that might be having a failure of some sort. More tomorrow....

 

[Blue-Fox]

Could it be a relay playing up?
I have a 770D but havent yet had an electrical issue with it so I dont know any of the electrical system...yet.

I love this machine, it's the one I would keep if I sold all the rest. I'm sure this is a more or less minor issue I'm just not well educated on these machines.

 

[Pickawinna]

I love this machine, it's the one I would keep if I sold all the rest. I'm sure this is a more or less minor issue I'm just not well educated on these machines.

Yeah I love my 770D as well. Lost of the good old school machines but still has the comfort factor when operating.
Keep me updated please with your problem.

 

[Blue-Fox]

Dealership ordered me a new CMU dash and its here. I did not get a chance to plug it in and test it out...

 

[biggrader]

When replacing the dash and powering up the first time, you will need to enter the hours of the machine. Ask your dealer for the exact procedure to do this. If you make a mistake and enter a wrong number at the wrong time, there is no going back. Even the service tech cant change it. You will have to remove, send to to the factory and have them reset it, and pay for those services. Ask me how I know.lol

 

[Blue-Fox]

When replacing the dash and powering up the first time, you will need to enter the hours of the machine. Ask your dealer for the exact procedure to do this. If you make a mistake and enter a wrong number at the wrong time, there is no going back. Even the service tech cant change it. You will have to remove, send to to the factory and have them reset it, and pay for those services. Ask me how I know.lol

Thanks for the heads up, I was told it needs to be flashed, then told it does not. Then the dealer told me its just plug and play and only displays what the computer tells it... So I'm going to try to get the old unit to work again and get the exact hour meter reading

 

[Blue-Fox]

When replacing the dash and powering up the first time, you will need to enter the hours of the machine. Ask your dealer for the exact procedure to do this. If you make a mistake and enter a wrong number at the wrong time, there is no going back. Even the service tech cant change it. You will have to remove, send to to the factory and have them reset it, and pay for those services. Ask me how I know.lol

Been a busy spring here, YES, The dash panel did have to be flashed with the cabling hooked up in the machine and ECM !! I would have been screwed just like you said!! and of course found there was a payload and an update, the machine is going now and seems normal. Thanks for the help.