1999 SLS needing help with suspension issues
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Cadillac Seville / Cadillac Eldorado Forum Discussion, 1999 SLS needing help with suspension issues in Past Cadillac Vehicle Discussion; Hi my names Tyler and i just purchased my first Cadillac, a 1999 SLS, it has had the rear shocks ...
  1. #1
    tylerkeith1114 is offline Cadillac Owners Member
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    1999 SLS needing help with suspension issues

    Hi my names Tyler and i just purchased my first Cadillac, a 1999 SLS, it has had the rear shocks replaced with ones that do not have a plug in for the electronic suspension control stuff so i'm getting the top speed limited to 90 mph thing and the suspension codes. I know i have to install a resistor on each side and i have the resistors (4.7 kohm, 1/2 watt) I just wondered if anyone could tell me how and where to install them, do you solder them in or?. Pics would help greatly. Thanks for any and all help!

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    MoistCabbage's Avatar
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    The wires coming from the original shocks would have run up the rear control arms, and plugged into a harness connector. You should see the connector on or near the control arms. It would have been better if you had the old shocks so that you could cut the connector and short section of wiring off. If the connector still on the car is the female end, you can basically just bend the resistor wires so that they "plug in" to the connector. Then just secure the resistor, and weather proof the connector/resistor using a small water proof bag, and some electrical tape.

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    Submariner409's Avatar
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    Re: 1999 SLS needing help with suspension issues

    You also probably have other suspension problems because the rear shocks also incorporate air bladders for rear height control due to weight changes in the trunk and back seat. That system depends on the bladders, air lines, compressor assembly and height sensor(s).

    Speed limited to 90 might also be a wheel speed sensor fault - different from suspension. The resistors get plugged into the existing wiring harness pigtails that are (hopefully) bundled and wire-ties to the suspension arms or up in the fenderwell - they have 2-conductor connectors and the resistors get plugged in same as plugging a bent paper clip into a wall socket - insulate well.

    Learn how to pull diagnostic codes from your car's built-in code scanner/reader/memory. Use the proper year/button sequence in the sticky post just above this thread - "how to pull codes". Get and codes and whether each is Current or History. Write that all down and return to the sticky to open the link of code definitions - find the embedded links for definitions of all P, B, C, and U codes. Write down all your definitions found and post it all here.

    EDIT: basscatt is correct in his later post - You may not even have active suspension, in which case there are no suspension control wiring connectors - onlly those to ELC, and that's not suspension control - it's very different - it's rear height control.

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    basscatt's Avatar
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    Re: 1999 SLS needing help with suspension issues

    are you sure you have the F45 electronic suspension?

    check the RPO label on the underside of the spare tire cover in the trunk -
    if you don't see F45 - you don't have electronic suspension -

    NEXT - you need to discover the REAL reason -
    for the error message -

    check for Diagnostic Trouble Codes -

    if you don't know how - go here and read the ENTIRE post -

    http://www.cadillacforums.com/forums...odes-dtcs.html

    if you have any codes - post them here -
    ALONG WITH THEIR DEFINITIONS -

  6. #5
    tylerkeith1114 is offline Cadillac Owners Member
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    Re: 1999 SLS needing help with suspension issues

    Ok i pulled the codes, C1722 LR Damper Actutor open CKT; C1727 RR Damper actuator open ckt; C1738 Exhaust Solenoid Valve Short to Ground; C1760 LF Position Input Sensor Fault; C1761 RF position input sensor fault

    ----------

    And i do have the F45 suspension

    ----------

    Anyone have any input on what these codes mean?

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    basscatt's Avatar
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    Re: 1999 SLS needing help with suspension issues

    the resistors should take care of the C1722 and C1727 codes -

    C1738 Exhaust Solenoid Valve Short to Ground -
    the exhaust valve within the air compressor
    for the ELC system is shorted out -
    you might try removing the compressor -
    and cleaning it up -
    but chances are - you will need to replace it -

    the other two codes will require a little more diagnosing -

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    JimD is offline Cadillac Owners Connoisseur
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    Re: 1999 SLS needing help with suspension issues

    Quote Originally Posted by tylerkeith1114 View Post
    Ok i pulled the codes....C1760 LF Position Input Sensor Fault; C1761 RF position input sensor fault
    With F45 (and F55) suspension, there are suspension position sensors mounted to the body behind each wheel and connected to the lower control arms by a short length of round rod. The 'most common' issues are disconnected or missing connecting rods AND sensor wiring harness damage or not connected to the chassis wire harness properly.

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    tylerkeith1114 is offline Cadillac Owners Member
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    Re: 1999 SLS needing help with suspension issues

    I installed the resistors it fied the top speed ordeal I don't know if i even need the compressor so i might just leave it alone. The car sits level and i have no problems with it as long as it wont cause any problems

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    basscatt's Avatar
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    Re: 1999 SLS needing help with suspension issues

    Quote Originally Posted by tylerkeith1114 View Post
    I installed the resistors it fied the top speed ordeal I don't know if i even need the compressor so i might just leave it alone. The car sits level and i have no problems with it as long as it wont cause any problems
    -------------------
    without the ELC system working properly -
    the car MIGHT sit almost level when empty -
    but if you put anything in the trunk or back seat -
    the ass end WILL sit low - and you WILL bottom-out going over bumps -

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    tylerkeith1114 is offline Cadillac Owners Member
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    Re: 1999 SLS needing help with suspension issues

    Quote Originally Posted by basscatt View Post
    -------------------
    without the ELC system working properly -
    the car MIGHT sit almost level when empty -
    but if you put anything in the trunk or back seat -
    the ass end WILL sit low - and you WILL bottom-out going over bumps -
    But since it has regular shocks it shouldn't bottom out right? I'm not trying to sound dumb i'm just wondering.

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    Submariner409's Avatar
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    Re: 1999 SLS needing help with suspension issues

    Shock absorbers are not load carriers in their usual, normal configuration - they are suspension dampers - they will damp with the car jacked up and they will damp with the rear sagged due to load: shocks will NOT prevent sag due to loads - that's the job of springs, helper springs, and, in our case, air bladder-assisted shocks......... BUT, if you load the rear end and fully compress the (non-assisted) shock it bottoms out and any damping feature is out the window.

    For the flip side, an air assisted spring has a limited range of down travel. An air assisted shock retains full damping travel while compensating for extra loads.

  13. #12
    basscatt's Avatar
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    Re: 1999 SLS needing help with suspension issues

    Quote Originally Posted by tylerkeith1114 View Post
    But since it has regular shocks it shouldn't bottom out right? I'm not trying to sound dumb i'm just wondering.
    -------------------
    Cadillac uses a "soft" spring -
    just strong enough to support the weight of the car - when empty -
    that is how it gives that nice "Cadillac ride" -

    that is the reason for the ELC - Electronic Leveling Control system -
    to maintain proper ride height - regardless of the weight in the car or trunk -

    your car has special rear shocks -
    they are "regular" oil-filled shocks -
    that have air bladders built into them -

    the sole purpose of "regular" shock absorbers -
    is to stop the springs from bouncing -
    they can not/do not support any weight -

    the purpose of the built-in air bladders - in our "specialty shocks" -
    is to raise the body of the car - to maintain proper ride height -

    so air-assisted shocks must do two separate jobs - at the same time -
    1) stop the springs from bouncing -
    2) lift and support the body of the car - when loaded -

    if the air compressor can't inflate the bladders within the rear specialty shocks -
    the shocks can't "help" the springs support the weight of the car -
    so the rear of the car WILL sag -
    and it WILL "bottom out" going over bumps -
    if there is any additional weight in the car -
    dou1t2 likes this.

  14. #13
    nzane1 is offline Cadillac Owners Member
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    Re: 1999 SLS needing help with suspension issues

    A 1999 seville came without f45/55 suspension? Never heard of that. Do the conversion kits compensate for spring load/levling to eliminate "bottoming out"?

  15. #14
    MoistCabbage's Avatar
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    F45 - CVRSS
    F55 - MagnaRide

    Concerning last gen Sevilles:

    F45 was standard on all STSs with a build date before 2/15/02. It was also available on the SLS in some years.

    F55 was standard, and exclusive to STSs with a build date of or after 2/15/02.

    "Conversion" kits come in different configurations. Most are just overpriced, passive, ELC compatible dampers, that come with a plug and play resistor to fool the computers. As long as they work with the ELC system, there will be no sagging or bottoming out.

    If they're not ELC compatible, they use helper springs. They provide a harsher ride, and will still sag under heavier loads.

  16. #15
    EcSTSatic's Avatar
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    Re: 1999 SLS needing help with suspension issues

    Seems like this is the age where this vintage is beginning to fail. It's a shame that manufacturers are discontinuing parts right when they are needed.

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