I think she's pressurized to 220 psig (not absolute) so you would need the Scan tool and wiTech software to draw it down I believe to monk with it or refill it. The refill toolkit for it of course has a guage but it's like $500 new.

 

Please also keep in mind that QL is a "closed" system filled with nitrogen gas. You don't want to do anything that risks even a minor leak.

 

Yeah the system is filled with 175 psig of class 5 nearly pure nitrogen and is closed in the sense that it moves nitrogen back and forth from springs to storage tank. It will draw in air to make up for leaks, however. Pressures can reach 220 in some parts of the system. One needs a dealers type DTC to properly check and fill the system and some mass calculation expertise.

The procedures call for air suspension refill tool which is basically the typical hose, valve, regulator, and gauge you see on gas welders. I suppose if you know your way around gas welding tanks you could do it without the special tool, dunno.

You check the pressure at the storage reservoir which is under the floor panel behind the seat (tilt the seat forward for access). The fill fitting is on one side, passenger I think. Not much clearance, you will need a 90 degree quick coupler on the end of the hose.

 

According to the scan tool, there is only 65psig in the system. And it won't let me change right height with the scanner because it reports Low Air Mass. So I guess the next step is to charge the system and try to find the leak.


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Dealer won't loan me or sell me the adapter that goes onto the reservoir. Is there an after market one that can be bought? I have 99.99% nitrogen as well as a regulator and gauge to supply 175psi to the system. And I can also perform the routines to charge each spring as the procedure calls for. Just don't have the adapter!

Once it's charged, I can monitor it to see how quickly it goes down and then start to look for leaks.


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Just use the Low Side Adapter from R134 AC Gauges

 

I don't recall anyone mentioning the type of quick coupler they use on the tank. Dunno if it will help to google for images for air tank quick couplers or air hose fittings and match one up with the tank. A long shot, but you could get lucky.

 

Not having much luck with this. Anyone know what fitting is used to attach to the reservoir to refill the system?

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No bubbles yet. I've sprayed the shock towers, pump fittings, and valve block fittings. Nothing.

There have been times in the recent past where the compressor does run (and run and run), but nothing happens (ie: ride height does not go up). Eventually it shuts off due to overheating.

If there was a leak, and the reservoir was low (65psi) would that affect the shocks in anyway? Because they are not going lower. Ride height is staying at Normal Ride Height.

Also, if I'm understanding you correctly, there should never be a point when the system drops below 175 psi because the compressor should be able to make that up?


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Looks like my edits crossed paths with your message, as it looked like you were on the right track and I was adding nothing.

The compressor can compensate for slow leaks but it cannot make up for a major leak or refill empty tanks. Air will slowly drain away as the compressor can't keep up. I believe once pressure falls below a certain threshold it stops trying.

I hear leaks can be frustrating to find. I don't have any tips for you, sorry. It looks like just putting as much pressure in as you can safely, and looking for bubbles. If your system is holding at 65 psi, perhaps its a valve body issue or a leak that only happens at higher psi. You will probably need to spray all the hoses and air bags as well as the pressure vent. I hear the most troublesome area is the fittings at the top of the front shock towers.

 

That doesn't look like the right part. Here is what the end of the tank looks like:



I found one kit on eBay (that has long since expired) that looks like it has the adapter needed. The adapter in the middle is the one you linked too. The one on the left is the one that has the valve on it that is detailed in the procedure. I believe the part number is 10247-2.



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So I took it to the dealer today. They recharged the system and tested for leaks but didn't find any. What's weird is they can control each shock individually (ie: cause it to vent to atmosphere and refill) they can discharge the system completely and refill it but when they try to initiate a change of ride height (like Normal to OR1) the system doesn't go anywhere. The compressor runs, and eventually times out, but no codes are thrown. After 5 hours of them working on it I just had them recharge it and end the service visit because they seem to be out of ideas.

So $600 later, I still don't know what the problem is. They suspect electrical though but they aren't sure. This is starting to feel like the Achilles Heal of the Overland model.


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More details to add. On the way home the compressor was kicking on every 2-1/2 minutes for about 30-40 seconds. I stopped at my mechanic and had him read the system pressure to see what the new baseline was. In Normal Ride Height, the system pressure is now at 113 psi... which surprised me because I thought it was supposed to be 175?

Does the system pressure change depending on ride height? Is there a table that shows what should be in the reservoir in Park, Normal, OR1 and OR2?

It makes me wonder if the reason the system wouldn't respond to the techs request for ride height adjustments (just compressor started to run) was because the compressor was first trying to make up the low system pressure? I hate this because I don't want to second guess the dealer, but it also cost me a lot of money and the problem is not solved.


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Almost sounds like the system is disabled. The compressor should not be running that much unless you are changing levels, there is a leak, the compressor is weak, or the valve body is sticking.

According to the FSM "Using a scan tool, ride height can be changed regardless of the engine state (running or not), doors or liftgate state (open or closed). The only condition necessary is that battery voltage must be greater than 10.5 volts"

"The valve block mechanically controls the flow of air in the system and maintains the pressure in the reservoir, and in each air spring individually. Valves and solenoids in the valve body open and close to increase or reduce pressure to air lines that connect to each pressurized component allowing the system to move each corner of the vehicle up or down as necessary. All wiring connected to the valve block is directly from the Air Suspension Control Module (ASCM) which fully controls the valve body. The ASCM determines pressure from an internal pressure sensor in the valve body."

The DTC has pre-program routines to test the system. After they filled the system, they should have been able to command ride height changes. Could be a bad ASCM, but I don't recall anyone reporting that here. There have been several failed compressors.

You may want to PM Jeepcares who may be able to direct you to a dealer that knows whats going on.

 

What I find interesting is that when I read the procedure for filling the system, it says to fill the reservoir to 175psi. Then charge one spring and top up the reservoir again. This is repeated for each spring. In the end, my assumption is the system should be at 175psi. The tech who was working on my vehicle though refilled the reservoir and then turned off the Nitrogen to it and filled all the springs. He claimed that the tank should hold enough to fill all the springs. But that seems to have left me with a system pressure of only 113psi.

Also, in order to command each spring to rise, i could hear the compressor moving air from the reservoir to the spring. To me, that would indicate that the valve body and logic are also working properly.

Your thoughts?


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You are suppose to refill the reservoir between the rear and front spring fill.

Did they do the Air Mass Calculation?

With a scan tool, using the routines under the Air Suspension Control Module (ASCM), perform the following:

• Command the vehicle to Normal Ride Height.
• Run the Air Mass Calculation routine on the air suspension system.
• If necessary, add to the system or deflate to atmosphere using the ASCM routines, then repeat the Air Mass Calculation routine again until system responds with Air Mass OK (188 - 216 bar-liters).


My thought, and just a guess, is either the system isn't full enough (they didn't do an air mass calculation) or there is badly behaving controller, it won't do ride heights. Perhaps disconnecting the battery for a minute would reset it. Otherwise there are a few things, like a door open, that would stop ride height changes... but the dealer scan tool is suppose to be able to over-ride those safety features when battery voltage is more than 10 volts or so.

I forget, did you say you saw the height push button flashing when you pushed it to go to ORA, or was there no response?

 

I don't know if they were flashing or not. Didn't look in. I know that right now I can go from Normal to OR1 in the driveway but it fails to go to OR2. End up getting Service/Repair Air Suspension message eventually.


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I don't know if they were flashing or not. Didn't look in. I know that right now I can go from Normal to OR1 in the driveway but it fails to go to OR2. End up getting Service/Repair Air Suspension message eventually.

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Hey JeepGC4me,

TSB 08-034-12 may relate to your vehicle:

SUBJECT:
Flash: Service Air Suspension Message And/Or U0415-00 And/Or C159E-15 Set
OVERVIEW:
This bulletin involves reprogramming the Air Suspension Control Module (ASCM) with new
software.
MODELS:
2011 - 2012 (WK) Grand Cherokee
NOTE: This bulletin applies to vehicles equipped with Quadra-Lift (TM) Air
Suspension (sales code SER) built before May 1, 2012 (MDH 0501XX).
SYMPTOM/CONDITION:
The customer may experience a "Service Air Suspension" message. Upon further
investigation the Technician may find that U0415-00 Impliable Data Received From
Anti-lock Brake System (ABS) or C159E-15 Air Pump Temperature Sensor has been set
active or stored.
Also if the vehicle is driven in extremely cold temperatures (-30C/-22F) the ASCM should
be updated with the new software. The new software will allow the air compressor to
continue to operate until -40C/-40F.
Updating the software will correct the conditions listed above.

 

By the way, were did you get the 175psi number the other day?


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That probably rules out the controller. It seems like either the compressor is too weak to pressurize the springs enough to go into ORA2 or there is a low fill. Perhaps the dealer's nitrogen tank was low. But I'm just guessing.


The 2011 FSM has these words, dunno if there are any updates:

The regulator on Air Suspension Refill Tool - is preset to 12 bar (175 psi) (as read with a scan tool, the gauge reads tank pressure only). When connected to the reservoir and the valves open, the pressure will equalize to 12 bar (175 psi) in approximately 10-15 seconds. A hissing sound can be heard while the nitrogen is being transferred and the sound will stop when the pressures are equalized.

6. Fill the reservoir to approximately 12 bar (175 psi) by fully opening the valve (2) on the nitrogen tank (3) and the valve (6) on Air Suspension Refill Tool.

7.When the pressures are equalized, close the valve (6) on the tool.

8.With a scan tool, using the routines under the Air Suspension Control Module (ASCM), perform a Short Fill on one rear air spring, verify that the air spring is seated properly, then perform a Complete Fill on that spring.

9.Repeat step 8 on the opposite rear air spring.

10.Fill the reservoir again by repeating steps 6 and 7.

11.With a scan tool, using the routines under the Air Suspension Control Module (ASCM), perform a Complete Fill on each front spring and shock assembly."

Then they are suppose to do the Air Mass verification. If the Air Mass was OK, the compressor may be weak.

 

To follow up this thread... had to go back to the dealer again because the compressor has been running almost non-stop for a week now. Only time it seems to stop is when it overheats.

When the tech asked the pump to stop from his computer, it didn't stop either. Found out that one of the relays was stuck ON. It's a funny relay, green, and in a separate compartment above the TIPM fuse box.



He didn't have one in stock, so he just took a standard relay with the same pin out configuration... except for whatever reason that relay was allowing the 40A fuse for the compressor to continually blow. It blew 3 fuses in a row. He suspected the compressor was drawing too much current, but first he tries to bang the green relay around a bit and the contacts dislodged. Put it back in again and it worked this time... and not blowing fuses anymore either. What's so special about this relay? Apparently it's not a standard relay, although the pin out is just like any other 30-40Amp relay.

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That green box is more than a relay, its also like a circuit breaker. That part number is used in many Mercedes vehicles. For the WK2 it protects the compressor motor. An overload relay operates relatively slowly allowing the motor to draw higher starting currents before tripping. So think of the green box as a relay with a slow reacting circuit breaker. The other relay probably is internally wired differently and blew the fuse.

 

Ongoing air suspension issue thread.

I'm sorry I don't have any pointers here but, I am really interested in this thread as we own the same vehicle year. I like to troubleshoot and repair stuff so I'm very interested in the final solution.

 

The compressor has, again, started running all the time and stayed on, even after the vehicle was turned off. Removed the "relay" and reinserted it... pump resumed. Removed "relay" and banged it gently, reinserted it, pump stayed off. I've ordered a new relay. Will take a couple of days to get it. Will update after it's replaced.


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To continue the development of this saga... got the new relay and installed it. But the compressor still runs way more than I ever thought it did before. It runs when it's supposed to, but then it also comes on a whole lot when it shouldn't. There's no doubt that it is slowly killing the compressor. It's "tone" has changed several times in the last couple of months and it no longer has the power to lift the Jeep to Off-Road heights. Yet, I really don't want to replace the compressor until I figure out why it runs and runs, or I'll just kill a new one too.

Went back to the dealer... another $500 of labor. They tested the wiring from the ASCM to the valve block and compressor. It tested good. They did find a couple of pins on the connector that were "loose" and have replaced them. Checked for leaks in the system again. None found anywhere. They also checked the airmass and it says there is enough air in the system. But after having it back for a couple of week or so now, it's still not solved.

Interestingly, the Jeep was parked at an airport for 7 days last week and never lost any ride height. Tank pressure is still unchanged. But the compressor is still running and running. Very frustrating.

Did manage to find the correct adapter to add nitrogen into the system at my mechanics instead of the dealer... hopefully.



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To continue the development of this saga... got the new relay and installed it. But the compressor still runs way more than I ever thought it did before. It runs when it's supposed to, but then it also comes on a whole lot when it shouldn't. There's no doubt that it is slowly killing the compressor. It's "tone" has changed several times in the last couple of months and it no longer has the power to lift the Jeep to Off-Road heights. Yet, I really don't want to replace the compressor until I figure out why it runs and runs, or I'll just kill a new one too.

Went back to the dealer... another $500 of labor. They tested the wiring from the ASCM to the valve block and compressor. It tested good. They did find a couple of pins on the connector that were "loose" and have replaced them. Checked for leaks in the system again. None found anywhere. They also checked the airmass and it says there is enough air in the system. But after having it back for a couple of week or so now, it's still not solved.

Interestingly, the Jeep was parked at an airport for 7 days last week and never lost any ride height. Tank pressure is still unchanged. But the compressor is still running and running. Very frustrating.

Did manage to find the correct adapter to add nitrogen into the system at my mechanics instead of the dealer... hopefully.

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Would you mind sharing the info on this adapter?
that would mbe really helpful

thanks!

 

Been a while since I updated this thread.

I have been stuck twice with the vehicle losing pressure and ride height. But in the early March the system was filled, levelled, and then disabled. No solenoids operating, no compressor running. Vehicle has gone 6000 kms and has not lost any ride height or pressure in those 6-7 weeks. So no leaks in the fittings, hoses or air bags for sure. Today the Jeep is in for replacement of the compressor and valve block and all associated parts. I'm anticipating a HUGE bill, but I REALLY hope this fixes it once and for all. Fingers crossed.


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Been a while since I updated this thread.

I have been stuck twice with the vehicle losing pressure and ride height. But in the early March the system was filled, levelled, and then disabled. No solenoids operating, no compressor running. Vehicle has gone 6000 kms and has not lost any ride height or pressure in those 6-7 weeks. So no leaks in the fittings, hoses or air bags for sure. Today the Jeep is in for replacement of the compressor and valve block and all associated parts. I'm anticipating a HUGE bill, but I REALLY hope this fixes it once and for all. Fingers crossed.

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I think they are on the right track of replacing the compressor. I had a service air suspension soon and immediately. Dealer took three days to diagnose it and replaced that green relay but eventually replaced the compressor. My compressor did not run continuously as yours is doing but once they put in a new compressor I have had no other error messages or issues. I have tested this under pressure by taking it out on rought trails for 2 days and raising up to OR2 and back to OR1 many times throughout the days.

 

Thanks for the update.

 

Hoping your compressor an valve block does the trick.

Thanks for the update.