Automatic Level Control
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 10 of 10
Like Tree1Likes
  • 2 Post By Mark C
Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, Automatic Level Control in Past Cadillac Vehicle Discussion; Hi Everyone, An question for the experts. I have replaced just about everything I can think of in an attempt ...
  1. #1
    Glock3540 is offline Cadillac Owners Member
    Automobile(s): 2000 Base Deville (Now A Slightly Modified Mutt). 2011 E-250
    Join Date
    Jul 2010
    Location
    Just Outside Nashville,TN.
    Age
    52
    Posts
    51

    Automatic Level Control

    Hi Everyone,
    An question for the experts. I have replaced just about everything I can think of in an attempt to repair my automatic level shocks on my 2000 Base Deville.
    I have replaced the shocks, air lines, and the height sensor (factory OEM and kind of pricey!). I have taken off the compressor and tested it and it is in excellent shape, ZERO moisture of any kind. I have also replaced the dessicant in the dryer with Crystal Kitty litter (very easy to do). I have traced wires for any fraying and the relay(s) and fuses all check out perfect.
    My system NEVER tests itself like others on this forum say their cars do on initial startup. I had to hot wire the compressor to the battery to get the shocks to inflate. Once inflated, they hold pressure and I have Zero leaks. It has remained rock steady at the inflated height for weeks.
    I bought an Electronic suspension ECM (part # 591-06564) off ebay to eliminate the only thing I have not checked or replaced. When I received it and took off the rear seatback to access the ECM to replace it, I could not locate it. All Data states it is behind the rear seat back passenger side. I looked and looked and all I could find was a Rear Integration Module part # 25662833.
    I then went back to All Data and evidently this part controls the Automatic Level Control on my car. My car does NOT have the F45 suspension. I believe the part I got off ebay is for a Deville with the Automatic suspension WITH F45 and I have the AUTOMATIC suspension WITOUT the F45 suspension.
    I have just emailed the ebayer for return instructions and have found the part I need that is much cheaper but before I buy; Is my logic here correct?
    ALLDATADIY clearly shows in their Automatic Level Control Suspension Schematics the difference between the two (and I also noticed on my car where this part I ordered might fit if my car did have the F45 option and it is an empty space).
    What do you experts think?

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    OldFart's Avatar
    OldFart is offline Cadillac Owners Fanatic
    Automobile(s): 2003 Deville DTS-133,000mi, 2002 HD Road King
    Join Date
    May 2011
    Location
    Orlando, Florida
    Age
    58
    Posts
    289

    Re: Automatic Level Control

    Do you have any DTC codes, that can help troubleshoot your problem. You've already confirmed the mechanical aspect is working by testing your pump etc., so it would appear the pump is not receiving 12 volt power during the test at startup or when the rear of the car sags. The pump receives its power from the ELC relay in the rear fuse box, check to make sure it is functioning correctly as well as it's 30A fuse is not blown. You should be able to hear the relay click, or feel it click with your finger on it, when the self test is performed a few seconds after the ignition key is turned on. Another source to check is that the ELC relay is receiving it's ground from the RIM (Rear Integration Module). All of these circuits are in the FSM.

  4. #3
    Glock3540 is offline Cadillac Owners Member
    Automobile(s): 2000 Base Deville (Now A Slightly Modified Mutt). 2011 E-250
    Join Date
    Jul 2010
    Location
    Just Outside Nashville,TN.
    Age
    52
    Posts
    51

    Re: Automatic Level Control

    Hi, I do not have any codes. I have checked and rechecked both the relay and the 30A fuse.
    I actually moved some of the relays around (identical part numbers) to different locations and all
    are OK. I did the same thing with the fuses.
    I just received my replacement RIM module today and installed it but no improvement.
    This is one of the most elusive problems I have ever had to solve on a vehicle.
    (The relay does not click and the "self test" has never worked in the 6+ months I have owned the
    vehicle). Is there any way to bypass the relay? I am just about out of ideas on what to do next...

  5. #4
    OldFart's Avatar
    OldFart is offline Cadillac Owners Fanatic
    Automobile(s): 2003 Deville DTS-133,000mi, 2002 HD Road King
    Join Date
    May 2011
    Location
    Orlando, Florida
    Age
    58
    Posts
    289

    Re: Automatic Level Control

    Assuming all the parts you replaced are good parts, the only thing left is the wiring. Are you familiar with reading a wiring diagram and using a DVM? It's a pretty simple circuit to test. If you don't have a diagram I can scan one as a jpg image and post it for you.

  6. #5
    Mark C's Avatar
    Mark C is offline Cadillac Owners Connoisseur
    Automobile(s): 1997 Seville STS, 2000 Seville STS
    Join Date
    Jul 2007
    Age
    56
    Posts
    1,668

    Re: Automatic Level Control

    2000 Devilles can have the electronic F45 suspension but it is an option, The spring options for the car are FE1/FE3 or FE7 HD if you have a limo or hearse, base Devilles usually have FE1 soft ride srpings. None of the various suspension packages and spring packages have anything to do with the functioning of the ELC system. The left side ride height sensor is the only one that gives the ELC system an input signal, it shares its data with the RSS system if you have the F45 electronic shocks, and the right side sensor is dedicated to the RSS system only.

    If you can disconnect the left side sensor link that connects to the control arm, and move the arm up towards the frame does the compressor come on at all?

  7. #6
    Glock3540 is offline Cadillac Owners Member
    Automobile(s): 2000 Base Deville (Now A Slightly Modified Mutt). 2011 E-250
    Join Date
    Jul 2010
    Location
    Just Outside Nashville,TN.
    Age
    52
    Posts
    51

    Re: Automatic Level Control

    Hi Mark C,
    You are correct, I have a base Deville with the FE1 suspension. The left side ride sensor is one of the
    first things I checked. It tested OK with my multimeter but the action of the arm was kind of "gritty"
    feeling so I replaced it with a new OEM part. Did not fix my problem.
    I have now replaced or at least checked out every part in the ALC system to no avail.
    The only other thing I can think of is; the system must send some sort of electrical signal
    starting when the ignition key is turned on. Maybe it is not getting current from whatever controls that?
    I'm not describing this very well, but not sure what else to do. I may have to break down and let a
    professional look at it. Sure wish I could figure it out myself.....

  8. #7
    OldFart's Avatar
    OldFart is offline Cadillac Owners Fanatic
    Automobile(s): 2003 Deville DTS-133,000mi, 2002 HD Road King
    Join Date
    May 2011
    Location
    Orlando, Florida
    Age
    58
    Posts
    289

    Re: Automatic Level Control

    Okay Glock3540, I printed the schematic and then scanned it as an image, hopefully you can see it. It's at 200DPI so you should be able to enlarge it for better detail. As you can see it is a very simple circuit. In the lower LH corner represents the sensor you replaced on the suspension. In the lower RH corner is the main ground for the pump, I would check this first because without it the pump will not run. In the top is the ELC relay that you swapped out. As you can see it gets it's signal from the RIM thru connector C10, this energizes the ELC relay which in turn sends 12volts to the pump. Since you do not feel the relay clicking, I would suspect it is not getting this signal from the RIM (which is on the LH side of the image), this signal is actually just a ground. With a DVM or multimeter you should be able to test each of the connectors and that will tell you where the problem is. If you don't have a DVM or multimeter, a test probe light will do in a pinch. The only thing I do not see in the schmatic is the location of the ground for the RIM (you can see the symbol for ground just below connector A7 & C2 at the top of the RIM). Without that ground the RIM cannot send the signal to the ELC relay.

    ELC, 2003 Deville.jpg

  9. #8
    Mark C's Avatar
    Mark C is offline Cadillac Owners Connoisseur
    Automobile(s): 1997 Seville STS, 2000 Seville STS
    Join Date
    Jul 2007
    Age
    56
    Posts
    1,668

    Re: Automatic Level Control

    Automatic Level Control General Description
    Vehicles Without Road Sensing Suspension

    The Automatic Level Control (ALC) system automatically adjusts the rear height of the vehicle in response to changes in vehicle loading.

    The ALC system consists of a height sensor, an air compressor assembly, an ALC compressor relay, an intake hose and filter, an air tube, and two rear shock absorbers . The air compressor assembly consists of an air compressor and an air dryer mounted on a bracket. The air compressor head is a replaceable part of the air compressor. The exhaust solenoid is a non-replaceable part of the air compressor head.

    The compressor is activated when the ignition is on, and weight is added to the vehicle. The exhaust solenoid is connected directly to the battery (+), enabling the system to exhaust with the ignition on or off when excess weight is removed.

    Vehicles With Road Sensing Suspension
    The Automatic Level Control (ALC) system automatically adjusts the rear height of the vehicle in response to changes in vehicle loading.

    The ALC system consists of the CVRSS control module, two CVRSS position sensors, an air compressor assembly, an ALC compressor relay, an intake hose and filter, an air tube, and two rear shock absorbers. The air compressor assembly consists of an air compressor and an air dryer mounted on a bracket. The air compressor head is a replaceable part of the air compressor. The exhaust solenoid is a non-replaceable part of the air compressor head.

    The vehicles rear vertical height is measured by the two CVRSS position sensors. These two position sensors convert this rear height measurement into an analog voltage (0 to 5 volts DC) which is read by the CVRSS control module. The control module then determines what action (exhaust, compress, or no action) shall take place. To compress, the CVRSS control module switches the low-side of the ELC compressor relay to ground.

    The air compressor is enabled (switched to battery only when the ignition is on. The air compressor is activated when a sufficient amount of weight has been added to the vehicle.

    The exhaust solenoid is enabled at all times. The exhaust solenoid is activated when weight is removed from the vehicle.

    Automatic Level Control System Operation w/o F45

    Raising the Vehicle
    When a load is added to the vehicle, the vehicle body moves down causing the sensor actuating arm to rotate upward. The upward arm movement activates an internal timing circuit and, after an initial fixed delay of 17 to 27 seconds, the sensor provides a ground to complete the compressor relay circuit. The 12V (+) circuit to the compressor is then complete and the compressor runs, sending pressurized air to the shock absorbers through the air tubes.

    As the shock absorbers inflate, the vehicle body moves upward rotating the actuating arm towards its original position. Once the body reaches its original height, +/- 25 mm (+/- 1 in), the sensor opens the compressor relay circuit, and the compressor is turned off.

    Air Compressor Head Relief Sequence
    In order to reduce current draw during air compressor starting, the height sensor performs an air compressor head relief sequence before air compressor operation. This sequence reduces the air pressure in the air compressor cylinder during start-up. The air compressor head relief sequence occurs as follows:

    Exhaust solenoid is energized.
    Air compressor is activated 1.3 seconds after the exhaust solenoid is energized.
    Exhaust solenoid is de-energized 0.5 seconds after the air compressor is activated.
    Lowering the Vehicle
    When a load is removed from the rear of the vehicle, the body rises, causing the sensor actuating arm to rotate downward. This again activates the internal timing circuit. After the initial fixed delay, the sensor provides a ground to complete the exhaust solenoid circuit, energizing the solenoid. Now, air starts exhausting out of the shock absorbers, back through the air dryer and exhaust solenoid valve, and into the atmosphere.

    As the vehicle body lowers, the actuating arm rotates to its original position. When the vehicle body reaches its original height, +/- 25 mm (+/- 1 in), the sensor opens the exhaust solenoid circuit, which closes the exhaust solenoid and prevents air from escaping.

    Air Replenishment Cycle
    The sensor actuating arm position is checked when the ignition is turned on. If the sensor indicates that no height adjustment is needed, an internal timer circuit is activated. After about 35 to 55 seconds, the compressor is turned on for 3 to 5 seconds. This ensures that the shock absorbers are filled with the proper residual pressure. If weight is added to or removed from the vehicle during the time delay, the air replenishment cycle is overridden, and the vehicle rises or lowers after the normal delay.




    Automatic Level Control System Operation w/ F45

    Raising the Vehicle
    When a load is added to the vehicle, the vehicle body moves down causing the sensor actuating arm to rotate upward. The upward arm movement activates an internal timing circuit and, after an initial fixed delay, the CVRSS control module provides a ground to complete the compressor relay circuit. The 12V (+) circuit to the compressor is then complete and the compressor runs, sending pressurized air to the shock absorbers through the air tubes.

    As the shock absorbers inflate, the vehicle body moves upward rotating the actuating arm towards its original position. Once the body reaches its original height, +/- 25 mm (+/- 1 in), the compressor relay circuit is opened and the compressor is turned off.

    Air Compressor Head Relief Sequence
    In order to reduce current draw during air compressor starting, the CVRSS control module performs an air compressor head relief sequence before air compressor operation. This sequence reduces the air pressure in the air compressor cylinder during start-up. The air compressor head relief sequence occurs as follows:

    Exhaust solenoid is energized.
    Air compressor is activated 1.3 seconds after the exhaust solenoid is energized.
    Exhaust solenoid is de-energized 0.5 seconds after the air compressor is activated.

    Lowering the Vehicle
    When a load is removed from the rear of the vehicle, the body rises, causing the sensor actuating arm to rotate downward. This again activates the internal timing circuit. After the initial fixed delay, the CVRSS control module provides a ground to complete the exhaust solenoid circuit, energizing the solenoid. Now, air starts exhausting out of the shock absorbers, back through the air dryer and exhaust solenoid valve, and into the atmosphere.

    As the vehicle body lowers, the actuating arm rotates to its original position. When the vehicle body reaches its original height, +/- 25 mm (+/- 1 in), the exhaust solenoid circuit is opened, which closes the exhaust solenoid and prevents air from escaping.

    Air Replenishment Cycle
    An air replenishment cycle (ARC) is commanded after each ignition-ON cycle. The purpose of the ARC is to ensure that the ALC system is operating at or above minimum air pressure (residual air pressure). The ARC occurs as follows:

    The EXHAUST SOLENOID IS ENERGIZED 20 seconds after the ignition has been turned on.
    The AIR COMPRESSOR IS ACTIVATED 1.3 seconds after the exhaust solenoid is energized.
    The EXHAUST SOLENOID IS DE-ENERGIZED 0.5 seconds after the air compressor is activated.
    The AIR COMPRESSOR IS DEACTIVATED 3.2 seconds after the exhaust solenoid is de-energized.
    SALVATORE and SALVATORE like this.

  10. #9
    Glock3540 is offline Cadillac Owners Member
    Automobile(s): 2000 Base Deville (Now A Slightly Modified Mutt). 2011 E-250
    Join Date
    Jul 2010
    Location
    Just Outside Nashville,TN.
    Age
    52
    Posts
    51

    Re: Automatic Level Control

    Thanks for the info guys. I had already printed and read this info off ALLDATA after Ranger's suggestion, but did not think about the test light.
    Not exactly sure where to look on the vehicle for the pump "ground". I have taken the pump off the vehicle several times
    and the only electrical connections going to the pump itself is 1 set of wires (4 total wires if I remember correctly) and when unplug
    this connector and give it 12V direct from the battery, the pump operates.
    Since the relay does not "click" ever, I also think it is not getting power to it. A ground that is not properly "grounded" could
    surely be my problem. Again, I do not have a clue where to look. I have traced the wire loom from the compressor, to the RIM
    (the best I could), the wires to the height sensor, etc., and never saw where any of the wires grounded to the vehicle.
    I will study this schematic some more and try to tell where my problem is.
    The first thing I am going to check is "Hot At All Times" and the "Hot In On" on the input side of the Relay. I would guess the
    "Hot In On" would be hot at all times when the ignition switch is on using this logic:
    "The sensor actuating arm position is checked when the ignition is turned on. If the sensor indicates that no height adjustment is needed, an internal timer circuit is activated. After about 35 to 55 seconds, the compressor is turned on for 3 to 5 seconds. This ensures that the shock absorbers are filled with the proper residual pressure. If weight is added to or removed from the vehicle during the time delay, the air replenishment cycle is overridden, and the vehicle rises or lowers after the normal delay."
    Will not have time to check it for a few days, will let you guys know how it turns out. Thanks Again.

  11. #10
    CadillacJack76's Avatar
    CadillacJack76 is offline Cadillac Owners Fanatic
    Automobile(s): 02 eldo collectors series, 98 eldo, 97 deville, 96+94 SLS,
    Join Date
    Oct 2003
    Location
    Long island New York
    Age
    37
    Posts
    219

    Re: Automatic Level Control

    Just wondering if you ever found what was causing your problem, I am having the same exact issue with an 02 dts and all I know is that the RIM is not grounding the yellow wire going to the ELC relay, if I ground it with my power probe everything comes to life, I replaced the RIM, with a used one, I know it could possibly be bad, i'm thinking its not bad because everything else in the car works properly, but Im hoping its not. This week I am going to get another one and see if the problem goes away, anyway, I just stumbled upon this post while searching for help so I figured I would chime in, even though it is an old post. Anyone have any input? Thanks, jack

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting