2500 Auto Level Rear Air Suspension

[grabinov]

Gents,

My new 2500 has the factory auto level rear air suspension. I was kind of undecided as to whether I wanted it or wanted to add my own system, but the truck that i found that best fit the bill had it, so I have it.

It has only one button in the cab, which essentially says "Alternate Trailer Height". It has only two "positions", On (Alternate) and Off (standard height). The feature can only be accessed with the truck stopped, and pushing it with no trailer on causes the rear of the truck to lower by a little more than an inch. I have not yet tried it with my fifth wheel attached, so I'll add more info once I do that this Saturday.

There is VERY little information on the system in the online manual, the paper manual or the CD that came with the truck. It essentially says that in the Alternate position, the truck will level the trailer (how would it know when the trailer rather than the truck is level) and that in the Off position it returns to stock rear height for "proper appearance". Strange...

First, it must level the Truck, not the Trailer. It has no way of knowing what angle my trailer is at, only what level the truck is at. Second, what is "proper appearance"? Do I really want to run with this high tech auto leveling system turned off when unloaded JUST so that my truck can have the traditional rear-high appearance that heavy duty pickups have when unloaded? Why is that appearance "proper"? Wouldn't you think they would have just made the whole thing auto leveling all the time?

Does anyone know if there is a really good description of the system and its design and function anywhere? A Ram engineer somewhere?

Auto manufacturers are not crazy. They didn't just put the system and the button on there cause it's neat. It must do something! Uhhhhh... Right?

 

[Powder Extreme]

When you are hitched up the truck will sit level instead of high in the rear. Ram assumes you will use the proper ball mount, gooseneck height, 5th wheel height, etc. to make the trailer sit level.

The best stability is achieved when both towing and towed vehicles sit perfectly level. The beauty of the auto air ride is that the truck will sit level with 200 or 2,000lbs of weight on the hitch.

The "stock appearance setting" is strictly that, just for appearance so the truck looks like every other tail high HD on the road. There is absolutely no value in having the truck sit tail high, the only reason they do is because handling is compromised when a vehicle sits tail low. The steering geometry is dramatically changed as well as blinding oncoming drivers with headlights now aimed too high. They have to start with the tail high so it sits level or close to it when carrying a load.

 

[grabinov]

Thanks for the confirmation Pow Pow. I'll have a chance to play with it on a two-day tow up to my dad's place up off Sourdough on August 16. We'll be up there for a week in case you see my red Megacab running around Boze.

 

[Powder Extreme]

Sourdough huh? Nice area! I looked at buying a few places up there. I'll be in Portland that week, but looking forward to a report on how your truck handles and rides, loaded and empty. I'm planning on converting my 2014 to full air ride when I get some time and depending on the results, might convert the duallie to full air ride.

 

[HAMMER77777]

I too, was among the first to order a 2500 with Air-Ride (she's a Hemi, don't hate). Anyway, since i don't ever tow, i just leave her on normal setting. If u go into your uconnect settings, u can actually access 3 more options. One, is transport mode, i think, which lowers your truck as low as possible for easy entry-exit. This helps my wife, who is small. There is also wheel alignment mode, self explanatory, and tire-jack mode, which disables the system during tire changing, for obvious safety issues. How do you like your Air-Ride truck? Mine's my first rig, And I Love her!

 

[grabinov]

Huh?

Last Saturday I towed my 5th wheel for the first time with my new 2014 with auto level rear air. I pressed the auto level button before hooking up (don't know why exactly, but that's what I did) and the truck lowered 1.5 inches. I backed in to the hitch, lifted the trailer jacks and, NEAT, the truck leveled back out. I only drove a few miles to my campsite before I unhooked (I had stored my trailer nearby after the last trip - to Mammoth Lakes, CA) but the air ride stayed on the whole time and performed flawlessly from what I could tell.

I DID have one interesting learning experience, which is that the running truck will neither raise nor lower when you unhook the trailer - it simply adjusts to level again! This means that when the trailer weight comes off, the truck does NOT raise - it was level with the trailer, and as you take the weight off, it will stay level. NEAT. But:

If the truck is shut off when you unhook, the pressure in the rear airbags will STAY HIGH, and, consequently, the truck will follow the trailer upward - alot - making it very hard to get the trailer unhooked, with the rear of the truck getting higher as the trailer does! Leave the truck running so it knows what you're doing or be prepared to lift your trailer 8" to get it off the truck! Either wat, All Good. But wait, there's more...

On Wednesday I hooked up to change spots (from Mammoth to Monterey by the way, and "No", you actually can't take a 5th wheel over Sonora pass even with a sweet new super-powerful truck. The sign that says 26% grade next seven miles mean exactly that. There IS a good turnout after the first mile. I have driven in these mountains for years but I'm not sure I've ever encountered a consistent 26% grade before though. Anyway...

When i hooked up I did NOT press the Alternate Level button before hooking up the trailer. I forgot. No big, I'll just press it now. I did, and this is what I got:

No, the truck did not flip upside down. I don't know why my iphone photos do. Anyway I got this message and the little icon next to the "P" for Park with the line through it. The Auto Level would not engage and no amount of off/on would fix it. Oh well, carry on. The truck clearly adjusted some, because it was pretty level.

2 hours later I pulled over at a fuel stop and decided to press the button after restarting the engine. I pressed the button and bing, it "engaged" and the message and icon went away, the compressor ran and the truck re-leveled.

Shouldn't some of this be described in the manual? The message? The Icon? The proper process? Who do I even ask? Is there a maximumu rated load for the Rear Air that is below the max payload? How could that be? Someone MUST know a Ram engineer that can explain how the system works, its modes and errors. Right?

By the way the truck otherwise performed flawlessly over a 400+ mile tow over many serious grades (including a small piece of Sonora Pass) at an average (reported) of 11.2 mpg. This was at an average speed of 46 mph (didn't seem that slow, but maybe i was just enjoying it). Despite reports from others, the exhaust brake was nothing short of remarkable to me at highway speeds and major grades on 89 and 50 coming down into Sacramento area. The new engine is awesome, loafing along at 1200 rpm with a 12,000 lb 5th wheel behind it.

 

[HAMMER77777]

Wish i had some info for u. I don't tow at all, just use mine as a Daily driver, for commuting. I just got The Air-Ride for a smoother ride...

 

[AH64ID]

Complete guess here... but the pressure in the bags was probably high enough that the computer didn't want to dump pressure. Did you look at the truck? Did any adjustment occur?

 

[grabinov]

Update

Complete guess here... but the pressure in the bags was probably high enough that the computer didn't want to dump pressure. Did you look at the truck? Did any adjustment occur?

The problem with the question about whether any adjustment occurred is that with this automatic system, it's very hard to tell. The weight of the trailer lowers the back of the truck, the truck compensates, or it doesn't. Since I can't see the pressure in the rear bags (wonder if that can be monitored by an Edge CTS), it is very hard to tell wether the end state is the result of the truck changing the pressure in the bags or simply the result of the tongue weight on the hitch at the prior pressure. With no trailer, you can definitely see the truck move when you press the button.

UPDATE from Today: I pulled back home today, and when I hitched up I remembered to press the button prior to lowering the trailer onto the hitch. Presto, worked like a charm. I think the truck needs to know that the weight is coming. By this analysis though, you also need to remember to press the button before loading something heavy into the bed.

I wonder what system monitors the pressure in the bags. The Body Control Computer? Clearly the instrument panel knows the status of the system.

 

[AH64ID]

The truck should only ever be at 2 heights, normal or 1" lower. I wonder if you can make a mark on the inside of the rear fender for where the top of the tire should sit?

 

[grabinov]

The truck should only ever be at 2 heights, normal or 1" lower. I wonder if you can make a mark on the inside of the rear fender for where the top of the tire should sit?

Yeah. I agree. It turns out that it's about an inch and a half. It's 18.5" to the bottom of the receiver, or 20" to the bottom of the receiver, with 18.5" being "level". That's a good point. If the receiver is 18.5" from the ground, then the truck either adjusted the air setting or the tongue weight is just right to push the bed down 1.5". I'll try it sometime both with and without the Auto Level to see what the difference is. It's just that I'm always on the way to somewhere far away and haven't taken the time to stop and figure all this out!

I wonder if the factory service manual has more detail on the operation of the system.

 

[AH64ID]

Unless you are very very heavy, i.e. overloaded, the truck won't have enough weight in it to squat 1.5" in the normal setting.

I am guessing that based on a stationary front axle the 1.5" at the receiver is 1" at the airbags.

If you find out more let us know, but so far I am liking the way the system works. I am curious what kind of pressures it runs at thou.

 

[grabinov]

From Chrysler Tech Authority:

"The air suspension system is an open system. The air suspension reservoir stores a specified volume of pressurized air for use when the system need to raise or lower the vehicle height. If an individual pressurized component of the air suspension system is damaged and air pressure is lost, the reservoir will hold any pressure left in the component. A scan tool is used to evacuate the component. After repair or replacement of the component, a scan tool can be used to refill the component from the reservoir.

The compressor cannot refill the reservoir and complete system if all pressure is exhausted, as in a compressor assembly or valve block replacement. The system will need to be filled at the reservoir with nitrogen. For complete filling of the air suspension system after a repair (Refer to 17 - Rear Suspension/Standard Procedure) ."

"The rear height sensors are wired directly to the Air Suspension Control Module (ASCM). The rear vehicle ride height information is used to determine and adjust the rear vehicle ride height. The ASCM then transmits the information on the CAN bus to the Air Suspension Unit (ASU). The rear height sensors have three wired circuits: height sensor power, signal and return."

"The Air Suspension Unit (ASU) is made up of two primary components, the compressor and the valve block. There is a single pressurized air line between the compressor and the valve block to maintain system pressure. Control of the air compressor and valve block is from the Air Suspension Control Module (ASCM). Diagnose the air suspension system using a scan tool.

Air Compressor The compressor runs to maintain air pressure any time the vehicle height is being changed or in the event of a small reduction in over all system pressure. Integrated reversing valves in the air compressor allow pressurized air to be moved in two directions, making this a closed system. There is a desiccant located inside the compressor for moisture protection, and an air suspension hose assembly attached to the air compressor (including a filter) which are not pressurized, and can be replaced as an assembly. If water is visible in the filter, the air suspension hose assembly and the valve block must be replaced. An air suspension temperature sensor is attached to the air compressor bracket to monitor ambient air temperature for protection of the compressor.

Positive voltage is from a 40-amp fuse located in the PDC, and a normally open compressor relay (ASCM controlled) located in engine compartment area, and ground for the relay and compressor are through a bolted on eyelet connection.

Valve Block The valve block controls the flow of air in the system and to maintain the pressure in the in each air spring which allows the system to move each corner of the vehicle up or down as necessary. Valves and solenoids in the valve body increase or release pressure to air lines that connect to each pressurized component. The ASCM determines pressure from an internal pressure sensor in the valve body. The air lines connected to the valve block are labeled for individual replacement."

 

[kcv67]

Old thread revived trying to figure the air system out it is an open system with closed system components. So correct me if I am wrong the air compressor just builds the pressure for the nitrogen pressure side that is in the bags and valves? So there must be a bladder in the tank that separates the open air system and nitrogen systems?

Casey

 

[Bob4x4]

Old thread revived trying to figure the air system out it is an open system with closed system components. So correct me if I am wrong the air compressor just builds the pressure for the nitrogen pressure side that is in the bags and valves? So there must be a bladder in the tank that separates the open air system and nitrogen systems?

Casey

No it is air only.The nitrogen after repair is only to ensure no moisture is induced into the system.The system can deal with the small amount likely to encounter during normal use

 

[kcv67]

So it is a complete open system. Air only?

 

[Bob4x4]

So it is a complete open system. Air only?

Pretty much sums it up

 

[AH64ID]

Pretty much sums it up

Is it the 3500 that is closed?

 

[Bob4x4]

- Rear Suspension/COMPRESSOR ASSEMBLY, Air Suspension/Description

DESCRIPTION


WARNING:
All pressurized air suspension components contain high pressure air (up to 220 psig). Use extreme caution when inspecting for leaks. Wear safety goggles and adequate protective clothing when inspecting or servicing the air suspension system. A sudden release of air under this amount of pressure can cause possible serious or fatal injury.


WARNING:
Support the vehicle by supplemental means before performing any work on the air suspension system to prevent the vehicle from changing height. Before any given component is to be serviced it must be deflated. Servicing the air suspension system without supplemental support, or with pressure in the specific component, can cause possible serious or fatal injury.


CAUTION:
When handling the air suspension compressor assembly, keep upright and carry only by the compressor itself or the primary bracket (bolts the assembly to the vehicle).

The Air Supply Unit (ASU) is located on the vehicle frame rail on the passenger side of the vehicle. The ASU contains the air dryer, compressor, exhaust valve, valve block, pressure sensor, and temperature sensor.

The compressor itself is suspended from the ASU mounting bracket by three spring loaded studs to reduce vibration and noise. The valve block is bolted to a mounting bracket that is in turn bolted directly to the side of the ASU mounting bracket. The ASU is serviced as an assembly.

The compressor cannot refill the reservoir and the complete system if all pressure is exhausted, as in a compressor assembly or valve block replacement. The system will need to be filled at the reservoir with nitrogen. For complete filling of the air suspension system after a repair (Refer to 17 - Rear Suspension/Standard Procedure) .

 

[sag2]

All FCA vehicles used a closed system that is not really closed. In theory it only moves air between the tank and bags, or bags and tank with the compressor. But to make up for any small leaks it can make up a small volume of air.