Need Help Understanding Air Suspension 2018 Dually

[dfindell]

When I hook up my 42 foot goose neck trailer the truck settles down with the load then the suspension rises. If I press the Alt Trailer Height button it lowers slightly. Question, is this adjustable? I need the truck to lower about another inch for better clearance between tail gate and bottom of trailer. What does the computer look for? Is it a pressure switch or mechanical limit. Any help understanding the mechanics of this suspension would be much appreciated.

 

[SnoKing]

When I hook up my 42 foot goose neck trailer the truck settles down with the load then the suspension rises. If I press the Alt Trailer Height button it lowers slightly. Question, is this adjustable? I need the truck to lower about another inch for better clearance between tail gate and bottom of trailer. What does the computer look for? Is it a pressure switch or mechanical limit. Any help understanding the mechanics of this suspension would be much appreciated.

I is what it is, and there is not much you can do to change it. If you have clearance issue, you would need to raise the trailer to match the truck. SnoKing

 

[dfindell]

I would like to understand the mechanics for the system. My air compressor shuts off at 125 lbs by a pressure switch. What tells the computer to stop filling the air bags and what tells the computer that the Alt Trailer Height is lowered and stops. The computer only works from external input and are these adjustable.

 

[SnoKing]

You will have to find someone to hack the PCM or what ever computer controls the rear air system.

In the mean time I found this about the system.

Ram 3500 Supplemental Air Suspension

The 3500 differs from the 2500 system in that it has rear leaf springs to support the truck's higher GVWR ratings. The addition of these springs can prevent some vehicle configurations from being able to obtain the lower “alternate trailer height” when unloaded as the leaf springs alone hold the vehicle at the normal ride height when unloaded. Therefore, these vehicles must be loaded before alternate trailer height can be obtained.

Auto Leveling – Time Delay
Like the 1500 system there is an added delay to give a “steel suspension like” behavior. However, with the additional load capacity of the 3500 system, a two stage strategy was developed. When lighter loads are applied the delay time is 10 seconds. Heavier loads will trigger a 20 second delay. Just like the 1500 truck, the engine should be left running when loading the vehicle if auto leveling is desired.

Key Off Strategy
Like the 1500 truck, the 3500 system will also make adjustments to maintain a target ride height after the ignition has been turned off. The air suspension system will stay active for 10 minutes after key off. However, the 3500 system will only lower during this time frame and the compressor is not allowed to run.

Door Open Strategy
Since the 3500 system is a rear axle only system, lowering of the suspension may occur while any door is open.

Trailer Hookup/Unhooking
The alternate trailer height may be used as a way to raise and lower the truck to minimize trailer jacking. The vehicle will always adjust to meet target ride height when using this feature as long as the air suspension system is not being overloaded. However, the following guidelines should be adhered to when hooking up and unhooking a trailer:

When using load distribution bars for conventional towing, select the height you plan to tow at (Ram recommends alternate trailer height) and then adjust load bars as needed (see "Hooking up a Trailer With a Weight Distributing Hitch").
When hooking up or unhooking a fifth wheel trailer, place the vehicle into Tire Jack Mode to prevent automatic height adjustments easing the ability to slide the kingpin out of the head without binding.
Never hook/unhook a trailer or place a load in the bed of the vehicle while it is in transport mode. Transport mode deflates the air bags to lowest safe level possible when selected and the air bags may be damaged by applying additional loads to the vehicle.

Hooking up a Trailer with a Weight Distributing Hitch (all trucks)

Set air suspension to normal ride height. No action is required if already in normal ride height. NOTE: The vehicle must remain in the engine running position while attaching a trailer for proper leveling of the air suspension system. NOTE: For Ram 2500/3500 trucksequipped with rear air suspension, normal ride height or alternate ride height can be used.
Position the truck to be ready to connect to the trailer (do not connect the trailer).
Under radio suspension settings, turn on jack mode. Jack mode will be canceled and procedure must be restarted if the vehicle is driven at speeds above 5mph (8kph).
Measure the height of the top of the front wheel opening on the fender to ground, this is height H1.
Attach the trailer to the vehicle without the weight distribution bars connected.
Measure the height of the top of the front wheel opening on the fender to ground, this is height H2.
Install and adjust the tension in the weight distributing bars so that the height of the front fender is approximately H2-H1)/3+H1 (about 1/3 the difference between H2 and H1 above normal ride height

).
The truck can now be driven. Jack mode will be canceled when driven at speeds above 5mph (8kph).

 

[dfindell]

This is a lot of great and useful information about the air bag suspension, I appreciate the time and effort to reply to my questions. Just wish a software code could be adjusted to accommodate the buyers towing needs. I would have been off not getting the air suspension and getting after market airbags.

 

[NIsaacs]

This is a lot of great and useful information about the air bag suspension, I appreciate the time and effort to reply to my questions. Just wish a software code could be adjusted to accommodate the buyers towing needs. I would have been off not getting the air suspension and getting after market airbags.

I would think the bags can only lower so much then the springs take over. I would think the non air bag truck would be too high for you, too. Can't you extend the gooseneck hitch? Will that cause an unlevel trailer?

Nick

 

[sag2]

To answer your question the system uses height sensors. Look for a sensor between the frame and suspension with a linkage connecting them. You could try and fool the sensor, but my guess is the system is smarter than that and will set codes and stop working.

 

[Cummins12V98]

This is a lot of great and useful information about the air bag suspension, I appreciate the time and effort to reply to my questions. Just wish a software code could be adjusted to accommodate the buyers towing needs. I would have been off not getting the air suspension and getting after market airbags.

Uh, no. The standard rear suspension sets much higher than the air ride especially in alt ride ht.

 

[EZeis]

They sell adjustable sensor links you can install and fine-tune. How much you can adjust I don't know. I didn't research them, just saw them available aftermarket. Just ball ends with an adjustable rod.
The gooseneck should be adjustable to give you more bed clearance. It's either bed clearance or unlevel trailer. So it's best to tow unlevel then destroy your bed. You can also look for a taller gooseneck ball to give more clearance. If you have the factory pucks, I believe B&W ram OEM ball is the tallest on the market.
I love my 18 3500 air suspension. It rides great empty or loaded. Always keeps itself level. The alternate ride height is great. Drops the rear to make the truck level and helps level out the trailer.


Earl

 

[Cummins12V98]

I run mine in ALT ride ALL the time as it sets nearly level. Height does NOT change even with 9,750# on the rear, see below.

A tip when unhooking your 5er go into settings, select suspension and then select tire jack mode. This will keep the truck from trying to level it's self. No need to do anything else as it will reset once moving truck or re starting.

 

[EZeis]

My truck won't do alternate ride height unless you have some load in the bed. So at empty it says no can do, no payload. 2018 tradesman 3500 SRW crew long bed 4wd.


Earl

 

[Cummins12V98]

My truck won't do alternate ride height unless you have some load in the bed. So at empty it says no can do, no payload. 2018 tradesman 3500 SRW crew long bed 4wd.


Earl

That’s true! All you need is three adults in the bed and hit the button. Then simply don’t touch it.