Air suspension gallery pressure question.
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Overlanding
Joined: Mar 2026
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Nope. Last. The reservoir only serves one purpose, to make a height change upwards faster.
Broken solenoid would not do it.
Basically the system starts the compressor and NOTHING opens for about one second. That is so the gallery pressure can get up to at least 150psi before a solenoid to anything is opened. Why? If a valve blocked opened right away and the gallery pressure was zero the strut could drop a small amount because air would go out, not in. So for a change up in height the compressor starts and reaches min psi, reservoir will open to assist, then one second later usually a rear valve block will open followed quickly by the front. If the reservoir was empty, you may often get "vehicle raising slowly" on the dash.
Broken solenoid would not do it.
Basically the system starts the compressor and NOTHING opens for about one second. That is so the gallery pressure can get up to at least 150psi before a solenoid to anything is opened. Why? If a valve blocked opened right away and the gallery pressure was zero the strut could drop a small amount because air would go out, not in. So for a change up in height the compressor starts and reaches min psi, reservoir will open to assist, then one second later usually a rear valve block will open followed quickly by the front. If the reservoir was empty, you may often get "vehicle raising slowly" on the dash.
so if pressure isn’t building. (Resulting in the fault). It’s either compressor failing Or a massive leak basically right at the compressor / center valve block.
Baja
Joined: Nov 2017
Posts: 5,013
Likes: 966
From: Green Bay, WI
Sorta. The compressor can be worn enough to not build pressure, think blow by of the piston head. It could have a leak at the exhaust port but I am pretty sure that is a Hitachi compressor issue not AMK. Or possibly some random other defect. Especially if it is not a real AMK. Aftermarket compressors are famous for random operating life spans from weeks to a couple years. Form there you would have to inspect all the lines form the compressor output to the center block and then to the front and rear blocks. The center block is wide open and does not regular air to the front or rear, only the reservoir. So the gallery consists of all the air line from front to back and right up to the compressor piston head.
At this point you need two things, soapy water and the GAP tool for more readings. Also let us know if this is a real AMK or an aftermarket. The fault code is a bit odd since reservoir comes last. Did you clear faults first before reading again? Could be an older fault from when it did last successfully raise and went to fill the reservoir but failed. That code is based both on how quickly PSI is reached and how long the compressor runs.
At this point you need two things, soapy water and the GAP tool for more readings. Also let us know if this is a real AMK or an aftermarket. The fault code is a bit odd since reservoir comes last. Did you clear faults first before reading again? Could be an older fault from when it did last successfully raise and went to fill the reservoir but failed. That code is based both on how quickly PSI is reached and how long the compressor runs.
Thread Starter
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Overlanding
Joined: Mar 2026
Posts: 20
Likes: 0
Sorta. The compressor can be worn enough to not build pressure, think blow by of the piston head. It could have a leak at the exhaust port but I am pretty sure that is a Hitachi compressor issue not AMK. Or possibly some random other defect. Especially if it is not a real AMK. Aftermarket compressors are famous for random operating life spans from weeks to a couple years. Form there you would have to inspect all the lines form the compressor output to the center block and then to the front and rear blocks. The center block is wide open and does not regular air to the front or rear, only the reservoir. So the gallery consists of all the air line from front to back and right up to the compressor piston head.
At this point you need two things, soapy water and the GAP tool for more readings. Also let us know if this is a real AMK or an aftermarket. The fault code is a bit odd since reservoir comes last. Did you clear faults first before reading again? Could be an older fault from when it did last successfully raise and went to fill the reservoir but failed. That code is based both on how quickly PSI is reached and how long the compressor runs.
At this point you need two things, soapy water and the GAP tool for more readings. Also let us know if this is a real AMK or an aftermarket. The fault code is a bit odd since reservoir comes last. Did you clear faults first before reading again? Could be an older fault from when it did last successfully raise and went to fill the reservoir but failed. That code is based both on how quickly PSI is reached and how long the compressor runs.
soapy water not seeing anything at the center valve block or compressor. Went ahead and did the center valve block rings etc while there since I had the kit.
clear faults. Same one comes up every times. It’s seconds after starting the vehicle attached is a video of what the gap tool shows during start up. Before firing the code.
the compressor is newer (very clean) and amk style but not sure 100% if it’s amk. Not seeing any marking yet.
Baja
Joined: Nov 2017
Posts: 5,013
Likes: 966
From: Green Bay, WI
Odd you are getting a reservoir fault. It it opening the reservoir valve as it should, ideally to assist in lifting because it would expect it to have air in there. But it should not be filling the reservoir first. Need more live values to the front and rear blocks valves because the rears should be opening shortly after the compressor start but not instantly. Also that 165 is Kpa, so that is like 24 PSI which is really, really low.
Baja
Joined: Nov 2017
Posts: 5,013
Likes: 966
From: Green Bay, WI
Probably because gallery pressure is not building so I expected that. I do knot know the minimum pressure needed off hand. Did you soak the reservoir with soapy water? They like to rust on the ends and on top. Since the reservoir is opening the air could be headed out that way. If you can locate 6mm or maybe even 1/4" push connect caps to block the line you cold remove the line going from the center block to the reservoir to seal it off and see what happens.
Thread Starter
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Overlanding
Joined: Mar 2026
Posts: 20
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Probably because gallery pressure is not building so I expected that. I do knot know the minimum pressure needed off hand. Did you soak the reservoir with soapy water? They like to rust on the ends and on top. Since the reservoir is opening the air could be headed out that way. If you can locate 6mm or maybe even 1/4" push connect caps to block the line you cold remove the line going from the center block to the reservoir to seal it off and see what happens.
Baja
Joined: Nov 2017
Posts: 5,013
Likes: 966
From: Green Bay, WI
No, saying cap the supply line to it not the tank. The reservoir is empty right now I am pretty dang sure. If there is any pressure, it's pretty low at maybe 2o or so psi. Not sure what you mean by backwards. The reservoir is, in essence, a container of air just like the struts. By closing it off to the system you are eliminating a potential leak source. That is all. If you want to drop if for better inspection, you can. You could even find a way to hook it up to any other compressor you have to see if it holds pressure.
Backing up a second here... on that video, what was gallery pressure after the compressor turns off for a few seconds. Video is too short. But it appeared that gallery pressure slightly increased after the reservoir closed? So with the reservoir closed, I wam wondering how long the gallery holds pressure. It may bleed down but it may help diagnose. Because if it is holding some pressure then maybe there are no leaks in the gallery but when the reservoir is open, it does not go up much which would make sense if there is a leak in it.
Backing up a second here... on that video, what was gallery pressure after the compressor turns off for a few seconds. Video is too short. But it appeared that gallery pressure slightly increased after the reservoir closed? So with the reservoir closed, I wam wondering how long the gallery holds pressure. It may bleed down but it may help diagnose. Because if it is holding some pressure then maybe there are no leaks in the gallery but when the reservoir is open, it does not go up much which would make sense if there is a leak in it.
Thread Starter
|
Overlanding
Joined: Mar 2026
Posts: 20
Likes: 0
No, saying cap the supply line to it not the tank. The reservoir is empty right now I am pretty dang sure. If there is any pressure, it's pretty low at maybe 2o or so psi. Not sure what you mean by backwards. The reservoir is, in essence, a container of air just like the struts. By closing it off to the system you are eliminating a potential leak source. That is all. If you want to drop if for better inspection, you can. You could even find a way to hook it up to any other compressor you have to see if it holds pressure.
Backing up a second here... on that video, what was gallery pressure after the compressor turns off for a few seconds. Video is too short. But it appeared that gallery pressure slightly increased after the reservoir closed? So with the reservoir closed, I wam wondering how long the gallery holds pressure. It may bleed down but it may help diagnose. Because if it is holding some pressure then maybe there are no leaks in the gallery but when the reservoir is open, it does not go up much which would make sense if there is a leak in it.
Backing up a second here... on that video, what was gallery pressure after the compressor turns off for a few seconds. Video is too short. But it appeared that gallery pressure slightly increased after the reservoir closed? So with the reservoir closed, I wam wondering how long the gallery holds pressure. It may bleed down but it may help diagnose. Because if it is holding some pressure then maybe there are no leaks in the gallery but when the reservoir is open, it does not go up much which would make sense if there is a leak in it.
Baja
Joined: Nov 2017
Posts: 5,013
Likes: 966
From: Green Bay, WI
Ok. Trying to figure out if that gallery pressure reading is faulty. 136kpa is way too static for my likes and wonder if that is, for all intents, zero. That could imply a bad sensor, bad wiring that is building resistance, etc. So something to keep in mind. But you can verify this by disconnecting any line in the gallery and see if air comes out and what the reading is. With the gallery open it should be zero. And if indeed 136kpa is indeed zero it would help diagnose and explain more.