What exactly does the "air suspension" do....
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  • 5 Post By MoistCabbage
Cadillac DTS Forum - 2006 through 2012 Discussion, What exactly does the "air suspension" do.... in Past Cadillac Vehicle Discussion; I have a 2007 DTS base. I looked around a bit on the forum, but I just would like some ...
  1. #1
    larryP03 is offline Cadillac Owners Member
    Automobile(s): 2007 Cadillac DTS
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    What exactly does the "air suspension" do....

    I have a 2007 DTS base. I looked around a bit on the forum, but I just would like some clarification.

    I do not have the electronic suspension, but I do have the rear "air shocks", if that's the correct term.

    What exactly goes on back there? I can't see how the shocks would be able to lift/lower the car since there are metal springs there too.

    Do they just firm up the ride to keep it from bottoming out if there is a load in the back?

    If the air lines on the shocks were to break, does the car sink to the ground? Or just bounce around as if the shocks were blown?

    Any clarification would be appreciated...


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  3. #2
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
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    It's not "air suspension", and they're not "air shocks". The system is ELC/ALC (Electronic Level Control/Automatic Level Control). The shocks are of the "normal" oil filled variety, but they have air bladders integrated into them (in between the top and bottom sections). The coil spring hold the rear at proper ride height when there is no additional load in the vehicle.

    Depending on weather or not the car has MRC, there is either one ride height sensor (in the rear), or one at each corner. It/they are mounted in the wheel well/s, and are connected to the control arm/s with a small connecting rod.

    When weight is added, the rear sags to lower than proper ride height. The electric compressor comes on, and inflates the bladders. Once the rear returns to proper ride height, the compressor turns off. When the weight is removed, the rear raises to above proper ride height. An exhaust valve in the compressor head opens, venting the system. When the rear lowers to proper ride height, the valve closes.

    The purpose of all this, is ride comfort. The system allows the use of softer coil springs, which provide a more compliant ride. In cars without ELC, stiffer springs are used, so that an acceptable ride height is retained, even when the car is loaded to it's weight capacity. This results in a harsher ride when the car is unloaded. With ELC, the spring rate is kept to a minimum, and ride height is increased by the air bladders, only when needed.

    If there is a leak in the system, or the compressor fails, rear ride height will not be effected (assuming the coil springs are not sagging or broken) when there is no additional load in the car, nor is damping effected. However, since the coil springs were never intended to support additional load by themselves, the rear will sag under the weight of passengers and/or luggage.

  4. #3
    larryP03 is offline Cadillac Owners Member
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    Thread Starter

    Re: What exactly does the "air suspension" do....

    Excellent description, I appreciate the help!

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    Eninety2 is offline Cadillac Owners Fanatic
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    Re: What exactly does the "air suspension" do....

    Quote Originally Posted by MoistCabbage View Post
    It's not "air suspension", and they're not "air shocks". The system is ELC/ALC (Electronic Level Control/Automatic Level Control). The shocks are of the "normal" oil filled variety, but they have air bladders integrated into them (in between the top and bottom sections). The coil spring hold the rear at proper ride height when there is no additional load in the vehicle.

    Depending on weather or not the car has MRC, there is either one ride height sensor (in the rear), or one at each corner. It/they are mounted in the wheel well/s, and are connected to the control arm/s with a small connecting rod.

    When weight is added, the rear sags to lower than proper ride height. The electric compressor comes on, and inflates the bladders. Once the rear returns to proper ride height, the compressor turns off. When the weight is removed, the rear raises to above proper ride height. An exhaust valve in the compressor head opens, venting the system. When the rear lowers to proper ride height, the valve closes.

    The purpose of all this, is ride comfort. The system allows the use of softer coil springs, which provide a more compliant ride. In cars without ELC, stiffer springs are used, so that an acceptable ride height is retained, even when the car is loaded to it's weight capacity. This results in a harsher ride when the car is unloaded. With ELC, the spring rate is kept to a minimum, and ride height is increased by the air bladders, only when needed.

    If there is a leak in the system, or the compressor fails, rear ride height will not be effected (assuming the coil springs are not sagging or broken) when there is no additional load in the car, nor is damping effected. However, since the coil springs were never intended to support additional load by themselves, the rear will sag under the weight of passengers and/or luggage.
    Is it safe to say all modern Cadillacs are equipped with ELC?

  7. #5
    MoistCabbage's Avatar
    MoistCabbage is offline Cadillac Owners 10000+ Posts
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    No, not all, but most since the mid '80's. for a time, all did have it.

  8. #6
    ral1960 is offline Cadillac Owners Fanatic
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    Re: What exactly does the "air suspension" do....

    I believe all the FWD Cadillac sedans had it (not sure about the new SRX).

    My old Fleetwood had it, but the compressor had died, so the previous owner rigged up an air valve under the bumper for manual inflation/deflation. Sometimes the plastic tube would pop out of the shock when loaded, giving me an instant low-rider at inconvenient times.

    The FE3 CTS and above-base STS have or had self-leveling rear shocks, which work differently (no compressor) but accomplish the same thing. Don't think the ATS offers them.

  9. #7
    facque is offline Cadillac Owners Member
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    Re: What exactly does the "air suspension" do....

    I have a 2008 Cadillac DTS that is now giving me a "bouncy" ride almost overnight.
    Does this mean it has air suspension? If so, where is the compressor located in the vehicle if it went out?
    Thanks.

  10. #8
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: What exactly does the "air suspension" do....

    The car - and none of ours - has "air suspension". Depending on model/option packages they have either a soft passive suspension or a "sports" active suspension - both use standard hydraulic struts/shocks and coil springs. The RPO (Regular Production Option) sticker under the spare tire cover gives that info. The passive suspension will show as FE1; the active suspension will show as F45/FE3. Google "2007 cadillac dts rpo codes" for lists of the option codes to see what's built into YOUR car.

    The rear shocks incorporate air bladders that control rear height in response to weight changes in the trunk or rear seat. The system is called ELC - Electronic Level Control and it has nothing to do with suspension firmness or control.

    This thread has been dead for 4 years. You might want to reset your forum view preferences to "View latest threads/posts first" - that way you avoid old history and members who have not logged in for years.

  11. #9
    Maximln is offline Cadillac Owners Enthusiast
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    Re: What exactly does the "air suspension" do....

    Before the "modern" Electronic Level Control system with the electric compressor that came out in 1978, Cadillac used the Automatic Level Control system which utilized a vacuum compressor that operated off of engine vacuum with no electric parts at all. The vacuum compressor didn't last nearly as long as the electric compressor!

    Max

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