Raise rear ride height - 1998 Cadillac DeVille

Raise the ride height? It looks like your front air shock absorbers have failed... of could be the air line manifold near the metal air storage tank.

Try this from my previous post....

Have a similar problem... My 2003 Lincoln Navigator was manufactured May 22, 2003 so it's the late model that came with the Intec 5.4 Liter DOHC V-8 (not the Triton engine).

I replaced the two front ride height sensors (one for each air strut) and replaced the one rear ride height sensor that controls the ride height for BOTH rear air struts. (Yours may have one ride height sensor for each of the rear air struts.) That solved the problem for a few months during the warm months, until the weather started cooling off. Then back to the same issue.

The front passenger air strut started releasing air from the solenoid (air block) making a "hissing sound." Replaced BOTH front air strut solenoids (connected at the top of each air strut). That also resolved the problem for a few days. After going all around the world, I discovered it's the Air Ride Control Module (ASM) that was the problem all along.

There is a switch under the rear of the car that actuates the compressor when the ride height falls below a preset level. The switch could be out of adjustment from being hit with road debris, causing the compressor to run al this time. Or there could be an air leak causing the air shocks to be constantly trying to raise the ride height. If there is an air leak, the back of the car would be much lower than the front, but still maintain ride quality.

The ride level system uses an air compressor and either an air type of shocks or a type of air billow to raise and lower the vehicle, there is an adjustment to set the ride height and it is located under the vehicle and there is a control lever or rod that should be connected between the rear axle and a switch that is mounted on the body of the vehicle, and there will be an adjustment slot in the control lever between the switch and the body, and that is how you would adjust the ride level height, but be sure that the vehicle can not drop any further down if someone is under the vehicle trying to adjust the ride height.

However, you might find that the control lever to the ride level has fallen off from the switch on the body or it has come loose from the rear axle, and it is just hanging there not operating the switch on the body that controls the the ride level compressor.

Sounds like it might have a bad height sensor.

switch is on the rear suspension , it senses ride height .

there is a sensor that reads the ride height of the car, it is called the ride height sensor, have it tested, it may be defective or not hooked up, the linkage comes off this sensor on a regular basis.

do you have just rear air suspension? here's rear only. 4 wheel different. Deler an run a diagnostic test with WDS machine and get fault codes.
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The air suspension system is designed to improve ride, handling and general vehicle performance for static, on-road and off-road driving conditions:

• Ride is improved by using an air type spring (the soft ride is inherent).
• Handling is improved by maintaining constant vehicle attitude.

The system consists of unique rear air springs, the air compressor, air lines, air spring solenoids, height sensor, air suspension control module, attachments and associated signals derived from both driver and road inputs. With these components and signals, the air suspension control module commands changes in vehicle height that are necessary for the load leveling features.
The load leveling feature rear air suspension (RAS) systems shall automatically make adjustments in vehicle height so that the vehicle is always at trim height and constant front-to-rear vehicle attitudes are maintained over the expected load range of the vehicle. Adjustments in height that are necessary to correct height differences between the vehicle's left and right sides for the RAS system shall be restricted to what can be reliably achieved with one air suspension height sensor.
The system uses one air suspension height sensor, a steering sensor, generic electronic module (GEM) and other vehicle sensors to measure driver and road inputs. The system changes vehicle height using an air compressor, two air lines and the use of air springs with air spring solenoids.
The air suspension system holds vehicle height when the rear hatch or any door is opened. The system stores rear vehicle height the moment any open door is detected. The system then maintains this height regardless of the addition or removal of a load. The system will return to its commanded height when all doors are closed or the vehicle speed exceeds 16 km/h (10 mph).
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Air Suspension Height Sensor
One air suspension height sensor is mounted on the vehicle. The air suspension height sensor sends a voltage signal to the air suspension control module. The output ranges from approximately 4.75 volts at minimum height (when the vehicle is low or in full jounce), to 0.25 volts at maximum height (when the vehicle is high or in full rebound). The air suspension height sensor has a useable range of 80 mm (3.2 in) compared to total suspension travel of 200-250 mm (8 to 10 in) at the wheel. Therefore, the air suspension height sensor is mounted to the suspension at a point where full rear suspension travel at the wheel is relative to 80 mm (3.2 in) of travel at the air suspension height sensor. The air suspension height sensor is attached between the No. 5 frame crossmember (upper socket) and the panhard rod (lower socket).
When the air suspension height sensor indicates that the rear of the vehicle is lower than trim under normal driving conditions, the air compressor will turn on and pump compressed air to the air springs. When the sensor indicates that the rear of the vehicle is raised above trim under normal driving conditions, this will cause the air to be vented from the air springs to lower the vehicle back to its trim height level
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• Uneven vehicle height

• Circuitry.
• Rear pneumatic fault.
• Air compressor assembly.
• Air suspension control module.

• Go To Pinpoint Test I .

they make aftermarket spring kits for air ride removal. you can also get used parts from an expedition without air ride. My personal opinion there isn't a great difference in ride quality the only advantage the air ride has is that it will raise the vehicle ground height when in 4x4

Whats your purpose for raising your car. Bcoz you know ? when ever you want more traction and grip, then you just lower down your car a bit instead of raising it up. It will be a bit tricky for you while handling at high speeds.