Eas help!

discostew

Well-known member
Sep 14, 2010
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Northern Illinois
Most times when a corner leaks down it's because the corner valve leaks the air back to the reservoir. Thats what I'm basing that statement on. I know I've had to get involved in a handful of cars like this. It usually ends up being the reservoir leaking, or the line that runs over the top of the reservoir. Crap from the road will build up between the frame and the reservoir and makes it rust thru. You should have a spray bottle with a little dish soap and lots of water. Get that bottom half of the cover out of your way and spray the shit out of anything that looks like it could leak air.
 

discostew

Well-known member
Sep 14, 2010
6,774
649
Northern Illinois
That's a good question about it leaking on rough road. Almost makes me wonder about the pressure sensor circuit. Most times these systems will flag a circuit fault pretty fast. Another air line that gets in trouble is down low between the radiator and a/c condenser. I assume it's also loosing pressure just sitting because it gets flagged on startup correct? Compressor runs for a long time after startup? You already know more about whats right or wrong on this thing. It's going to take a dealership tech a little over an hour to get to the place your already at.
Turn it off and watch the pressure on your scanner. Just leave the key on but not the truck running. Verify that the thing really is holding pressure. My guess is that it's leaking down.
 

nedarb2

Active member
Apr 28, 2018
42
2
canada
That's a good question about it leaking on rough road. Almost makes me wonder about the pressure sensor circuit. Most times these systems will flag a circuit fault pretty fast. Another air line that gets in trouble is down low between the radiator and a/c condenser. I assume it's also loosing pressure just sitting because it gets flagged on startup correct? Compressor runs for a long time after startup? You already know more about whats right or wrong on this thing. It's going to take a dealership tech a little over an hour to get to the place your already at.
Turn it off and watch the pressure on your scanner. Just leave the key on but not the truck running. Verify that the thing really is holding pressure. My guess is that it's leaking down.

You can only see the pressure when the system is raising as the sensor is in the center valve block. So when the truck is off this can’t be seen. I don’t have the iid to open the center valve block and watch pressure I just have the 4Dcan software
 

discostew

Well-known member
Sep 14, 2010
6,774
649
Northern Illinois
Ok, then see what the pressure is when you shut it off. Turn the key on 5 min later and see how much pressure is in it. Better be the same, or the computers right, it's got a leak.
 

nedarb2

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Apr 28, 2018
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Ok, then see what the pressure is when you shut it off. Turn the key on 5 min later and see how much pressure is in it. Better be the same, or the computers right, it's got a leak.
Doing that right now!

However I’m stumped on this. Once the vehicle raises to its target height, the center valve block closes off correct? Aka valves close from center to front/back. The system doesn’t stay charged. Therefor once vehicle is raised if there was a leak in the line from front to center or back to center, once the center valve block closes the compressor is going straight to the reservoir and pressure will build faster, which it doesn’t do.
There has to be something causing air to be consumed and get out of the system which only happens when driving on rough terrain aka the suspension is moving aka shocks go up and down. All of these suspected issues would happen all the time. I’m still not seeing something that makes a light bulb go off that explains why the suspension moving drains the reservoir.

I’m almost considering a chaffed or broken wire somewhere that’s triggering the exhaust valve to open to drain air when it shouldn’t. Maybe when the suspension is traveling it’s causing the wire to contact somewhere?? I don’t know when the exhaust valve should open other than lowering the vehicle....
For the reservoir to drain so fast there would be a MAJOR leak somewhere not just a trickle. Therefor isn’t it logical it’s dumping out the exhaust, so the question would be why is the exhaust valve opening to let it out?


IF I can confirm pending this pressure test that there is no reservoir leak, I’m going to buy some bolts tomorrow that fit into the valve block ports. I’ll plug the holes to the front /rear so that the compressor to reservoir is the only line open. That will Show me the rate of Reservoir air pressure build up knowing that 100% of the compressor is going to the reservoir without loss.
Then I can plug in the line to the front and back individually and see if the rate of build up slows. That will single out what line if any is giving me air loss in terms of singling out leaks but still doesn’t explain why rough terrain / suspension articulation causes major reservoir air loss. I’m sure driving around causes air loss too but less suspension travel = less air lost.
 
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discostew

Well-known member
Sep 14, 2010
6,774
649
Northern Illinois
If that was the case how could a corner valve let air from a corner back into the gallery? I'll try to find it spelled out in system description and operation but I know for a fact air can leak past a bad corner valve and back into the gallery. So because of that I always assumed that the air line at the corner valve was the end of the gallery.
 

discostew

Well-known member
Sep 14, 2010
6,774
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Northern Illinois
#11 is the valve that Isolates the actual reservoir, so your right about the reservoir itself being shut off in theory. But look at how the line going to out to each corner valve is really open all the way back to the compressor head and the pressure switch #12 is in that same gallery. The system watches that pressure switch and vents the system right before the comressor kicks on. That way it doesnt try to start up with 150 lbs of head pressure and fry the relay and fuse. The act of doing that is what sets the vent fault imediatly if you have the wrong software.
You can see in this diagram that the line to each corner valve must not leak.

Now you know more than the stupid kid your going to give $160 bucks an hour to get up to speed. You can fix this thing. I can tell just from talking to you here your smarter than that system.
 

nedarb2

Active member
Apr 28, 2018
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#11 is the valve that Isolates the actual reservoir, so your right about the reservoir itself being shut off in theory. But look at how the line going to out to each corner valve is really open all the way back to the compressor head and the pressure switch #12 is in that same gallery. The system watches that pressure switch and vents the system right before the comressor kicks on. That way it doesnt try to start up with 150 lbs of head pressure and fry the relay and fuse. The act of doing that is what sets the vent fault imediatly if you have the wrong software.
You can see in this diagram that the line to each corner valve must not leak.

Now you know more than the stupid kid your going to give $160 bucks an hour to get up to speed. You can fix this thing. I can tell just from talking to you here your smarter than that system.
Thanks stew.
That head pressure makes sense to me to exhaust away.
So what I’m going to do is pull the eas fuse and see if there’s a pressure build up. Maybe I’m not leaking air cause the exhaust valve isn’t opening when fuse is pulled but the lines to front and back are charged and not leaking out so I don’t loose. If that’s the case, knowing the front valve block and center are new this would mean my rear valve block is leaking into the system. Agreed? Holy I’ve come up with a theory to blame almost every part in the suspension system system now.

That also works with the idea I don’t loose air sitting over night. You need the rear shocks to compress during articulation to pressurize the air and leak past the rear valve block.
 

discostew

Well-known member
Sep 14, 2010
6,774
649
Northern Illinois
You do loose air sitting over night. Just not at the air spring. I don't think its any valves in your compressor because it would have to be bad AND the last compressor had to of had the exact same failure. Thats a long shot. My money is on one of those lines leaking. Frome experience it's most likely the one going to the front corner valve. Between the radiator and a/c condenser is a terrible place for a plastic hose to live.
 
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discostew

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Sep 14, 2010
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Northern Illinois
You know it's possible you have one of those lines in the wrong position. That causes all kind of strange stuff, and codes that make little sense. But check the lines for leaks again. Thats what most of them end up being. Yours isn't special.
 

nedarb2

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BINGO!!!!
Just went for a spin.
Pressure doesn’t drop to 120-140 when I’m on an uneven surface. It’s BUILDS to 120-140 from 24 (residual pressure after compressor cuts out). Holy crap holy crap holy crap. So air is leaking into the pressure sensor line. Exhausting out. Front valve block is new must be the back!!!!!!
 
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nedarb2

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Apr 28, 2018
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OK. still fighting this. new rear valve block went in tonight, went for a drive, and bang suspension error :mad: :mad: :mad:
it appears air from the reservoir is being lost immediatly upon hitting anything but level ground, aka suspension articulation still.
I dont believe i have a leak, and i KNOW there is no leak between front/rear valve blocks and the shocks as pulling the fuse and driving 6+ hours off road doesnt loose any ride height.

So again, back to the drawing board and the question remains - why am i loosing air when the suspension is articulating/being used very rapidly. which means why are the front/rear valve blocks opening,allowing air to be lost, instead of staying closed????????? should they exhaust air or try to add air to level the vehicle? it seems like its trying to self level constantly and air is just blowing out.... shouldnt they stay closed / cross valve open so air goes side to side??? :mad::mad:
 

nedarb2

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Apr 28, 2018
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Also - not trying to beat a dead
Horse here but I’m trying not to over look anything. Could this all be caused by the vehicle never having the software updated from the hitachi to amk?
 

discostew

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Sep 14, 2010
6,774
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Northern Illinois
Well, there is one more valve. It's called the reservoir valve. If you look at that drawing I posted, it could sure cause this. But I have also seen people cross the line locations on corner valves and cause all kinds of goofy shit like this. I have never seen pressure go up because of bumpy roads, I believe you but I have not experienced that one. So if a line was crossed I could see it pumping air backwards thru a valve that would seal that air on the other side.
 
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nedarb2

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Apr 28, 2018
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Well, there is one more valve. It's called the reservoir valve. If you look at that drawing I posted, it could sure cause this. But I have also seen people cross the line locations on corner valves and cause all kinds of goofy shit like this. I have never seen pressure go up because of bumpy roads, I believe you but I have not experienced that one. So if a line was crossed I could see it pumping air backwards thru a valve that would seal that air on the other side.


I’ve replaced all 3 valves (front, distribution, and rear) , are there 4???
I double checked all my lines and none are crossed. I made that mistake the first time ;)
 

discostew

Well-known member
Sep 14, 2010
6,774
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Northern Illinois
No only 3 vales. When the truck is running does the compressor run a lot? Does it run for a long time after you start the vehicle? And one other question is when does the thing fault out? On every vehicle start up?
 

nedarb2

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Apr 28, 2018
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Faults clear right away when re starting vehicle every time.
Faults occur within 15 seconds of being on in even ground. Compressor runs for about 10 seconds when car starts regardless of how long it’s been parked. Does not run if car is still and running. When On Un even terrain runs almost constantly as air pressure drops
 

nedarb2

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Apr 28, 2018
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C1a20 reservoir not filling fast enough.
Air is being used constantly in my opinion so air can’t build up in reservoir (compressor is trying to pump air into the struts directly when driving after air from reservoir is used up very quickly)