Bell 4206D Loss of Hydraulic Function

[Schrex]

He have a Bell scraper tractor that has no hydraulic function. This has a Parker iQan system. I am totally unfamiliar with this system. We checked over the entire tractor and the only thing to really note is the MDM (Display) has power but no visible screen. Just the green light on the back side of the monitor. I just located a pin out of the ECU so I have to check all of the connections there but any thoughts? I can't recall that screen ever working in the time we have had the unit. Would that cause the system to not work? Checked the machine for codes and come up with a clean bill of health. I was able to locate a new LCD screen to replace the monitor and have that ordered. I might have to get the dealer involved but would like to resolve in house.

 

[Questionable wizard]

First question to get a better picture of the situation, is this an electrical problem, or mechanical problem? On the 4206D I had experience with, the hydraulic pump coupler at the bellhousing wore out.

 

[Schrex]

I suppose it could be mechanical failure. I have not put pressure gauges on the machine yet. Is the attachment hydraulics it's own pump? We have steering so I assumed we had at least pump function. I have zero hydraulics at the rear. Have to check for signal at the solenoid block yet. We had a bunch of other issues with the machine we had to work our way through first that we're all electric related. Those are resolved now just the hydraulics for the scrapper are left. This thing has been parked for about 2 years and not used a whole lot prior to that. Im not a hydraulics guy for sure. Learning as I go here.

 

[Questionable wizard]

With the engine running, can you feel the hum of vibration on the discharge hydraulic line coming from the hydraulic pump? I.E., oil flowing through the line?

 

[DustAndRay]

I'd put hand on that discharge line with the engine running, feel for flow/vibration; check for a voltage signal at the solenoid block directly; see if the new LCD screen fixes the communication issue first

 

[Schrex]

I will be checking for flow and signal today at the pump and valve. I was finally able to get a copy of the original iQan manual off Parkers website. So know I have some wiring reference. Turns out the power light on the back of the display does have a function. Under normal conditions it should be a steady flashing light. If the light is solid it has a fault. Ours is solid, so we do have some sort of electrical fault but could be anything. It looks like there is only a couple circumstances that would cause total loss electronically. I will update as I figure stuff out.

 

[Schrex]

UPDATE! So we checked all mechanical and electrical spots for issues. All check out. We have been waiting weeks for a new LCD display to arrive from Sweden. It was my 600$ gamble as a complete monitor is north of 3500$. Replaced the display screen and hooked everything back up and wham bam all hydraulic function has returned and I can now see what the system can see on top of it all. So in short, if that display goes out you will likely not have hydraulics. Now I did some check with my operators and the couple part time techs I have and they all said the same thing about the screen not being able to be seen. I vaguely recall the display being very, very dim but something still there. I have only worked on this machine a couple times though. So if you loose hydraulic function check to see if the LED on the back side of the MDM has a LED light on. It should be flashing at normal operation. If it is solid there is a fault. Hopefully your screen works and you can see what is going on. All I can guess is that with the display board finally burning out it lost something in the CAN comm line and that made it unhappy because per the manual for the display installations, CAN disruption or power loss to the MDM are the only total shutdown issues that will occur. I suppose if you severed the harness to the valve block completely you would also have the same condition but I think you would see several codes for open circuits. This is only in the event you have a solid LED on the back of the MDM. If you have a mechanical problem you would see the flashing light (all okay electronically) under most circumstances. It was pretty cool leaning about a legacy iQan unit. They seem to be generally disliked from what I can see but I think that is most devices with a heavy electrical component. Hope this thread helps out another bloke someday! Have a great season!