Air Ride Suspension System Leak Detection and Repair

Air Ride Leak Detection

To the untrained technician, a winter air ride problem might lead you down the path that there is a leak in the system. However, chances are there are no detectable leaks. These types of faults are usually set by parameters from the air ride module for a specific action to cause an expected result.


It is a common occurrence on the coldest days of the year or a day with wide temperature variation, to get a customer call or visit complaining that they have a warning message on their dash telling them the air ride suspension system is malfunctioning, or there is a fault.

The customer may say that the vehicle is not riding low and that they do not notice any other problems. But, in extreme cases, the customer may see a message that the vehicle is too low. By the time it gets to your shop or sits for more than 30 minutes, the air suspension could be working just fine and the message could be gone, but a code for plausibility or a leak might be stored in the suspension module.

To the untrained technician, a winter air ride problem might lead you down the path that there is a leak in the system. However, chances are there are no detectable leaks. These types of faults are usually set by parameters from the air ride module for a specific action to cause an expected result. Think of it as an EVAP system. An EVAP system can’t see an actual leak, but it can detect a leak with a pressure reading.


Codes might be correlated with the time it takes for the compressor to replenish the reservoir, or the time it takes to carry out a trim adjustment. If it takes too long, the control module will assume there is a problem and puts the vehicle into a safe mode to preserve the compressor and airbags.

While these observations by the system could be the result of a leak, these faults are more likely the result of a weak compressor, sensor or a problem with the solenoids controlling the system.

Sensors
There are three types of sensor information a vehicle uses to trim the ride height and regulate the compressor: temperature, pressure and ride height.

Temperature is a significant parameter for air ride, such that air density and pressure can vary widely due to temperature. This is called Charles’s Law.

If a driver with an air ride suspension drives his vehicle home from work with an outside temperature of 32° F, and the brakes also heat the air in the bladders, the air’s volume in the bladder expands. If the driver parks the car overnight and wakes up to a 10° F morning, the air inside the bladder will have contracted and there will be less volume and pressure to support the vehicle. When he walks outside, the vehicle will be riding lower. Air temperature also impacts the reservoir. As the temperature decreases, the amount of air in the reservoir also decreases. This means there is less air to trim the vehicle.

Charles’s Law also applies to compressors. If air intake temperature is lower, the compressor can use denser air. In that case, the time to pressurize the reservoir should be reduced.

All air ride control modules regulate how long the compressor will run to keep temperatures inside at a safe range. The control module will look at ambient temperature and other factors to determine when, and how long, the compressor should run to generate the correct volume and pressure to fill the reservoir or trim the vehicle.

Outside an ambient temperature sensor or the mass airflow sensor can determine temperature. Some systems will have a thermocouple connected to the compressor. Measuring air temperature is critical because it will determine how much time it will take the compressor to fill the air springs and reservoir.

Hall-effect sensors measure travel at the wheels. These sensors also measure the ride height of the vehicle. But, the data generated is used to determine if a correction or adjustment was effective by measuring the time it takes to adjust.

Pressure sensors are typically mounted in the reservoir, compressor or control block. Most systems will measure only the pressure at the reservoir. Pressure sensor input is used to determine compressor output and not the pressures that go to the wheels.

Leak Detection
Most air ride leaks fall into two categories — those that can be seen with the naked eye and those that need a little help to be seen. The soapy water method might work for some larger leaks, but there are special aerosol leak detector sprays that can make tiny leaks more visible by producing smaller bubbles with better surface tension.

Some techs have had luck using small, sensitive microphones to hear leaks coming from air ride components. But, this method might not work in some noisy shop environments.

Codes
The codes for cold weather problems will typically include the words “replenish,” “reservoir,” “overheat,” “no pressure increase” or “timed out.” There are two main culprits for these codes: a weak compressor or a leak in the system. It is possible that a sensor in the reservoir is faulty, but this is extremely rare.

Codes may require a scan tool that can communicate with the air ride system, and the codes may be proprietary to the make and model. Also, a good scan tool can perform bi-directional tests and calibrate the system.

One of the main operating parameters for the air ride system concerns controlling the temperature of the compressor. Modern systems are dry and do not use oil to lubricate the piston and bore. Therefore, excessive heat can destroy the piston seal and bore.

You May Also Like

Buick Encore Alignment Service

Alignments are key to the health of the tires and some of the advanced safety systems like automatic emergency braking and lane keeping.

The 2012-2022 Buick Encore is based on the Gamma II platform that is shared with the Chevy Trax. This has been the best-selling Buick for several years. Like a lot of modern vehicles, the alignment specs are tight with almost no adjustments built in except for toe. However, alignments are key to the health of the tires and some of the advanced safety systems like automatic emergency braking and lane keeping.
Front Suspension
The front suspension on the Encore has a single lower control arm and MacPherson struts. Some models have a suspension dampener on the front bolt of the lower control arm. The part helps to control vibration that could be transmitted to the subframe. If the caster is out of specification, look at the bushings on the lower control arm for damage. Camber can be adjusted by installing cam bolts in the lower hole of the strut mount. This should give ±1.75 degrees of adjustability. Inspection of the lower control arm is a critical part of aligning the Encore. The arm can be bent due to curb strikes and the bushings can quickly deteriorate. Also, inspect the sway bar links for any signs the ends have play.
Rear Suspension
The Encore comes in front-wheel-drive and all-wheel-drive versions. Both versions use a trailing arm beam axle. The camber and toe for the front-wheel-drive version can be adjusted with shims. Unfortunately, there are no adjustments for the all-wheel-drive version. If camber or toe are out of specification in the rear, look for a damaged wheel. If the thrust angle is out of specifications, inspect the trailing arm bushings.

Live Axle Wheel Bearing Service

Replacing rear wheel bearings on a live axle rear suspension requires a few extra steps when compared to a unitized bearing.

Ride Height Sensors

If one of these sensors is replaced, it must be calibrated after it is installed.

Ride Control For Electric Vehicles

Replacement units are available from sources other than the dealer.

Brake Pad Edge Codes

The “Edge Code” can tell you information about a brake pad’s friction material.

Other Posts

Chassis Parts and Alignment Angles

Knowing why the adjustment is required is critical to performing the total alignment.

Suspension Upgrades – Selling Shocks and Struts

The question customers fail to ask is, what is “best” for their vehicle?

Air Ride Suspension Diagnostics

The key to understanding the logic of air ride systems is using service information.

Steering Angle Sensor Operations

It is important for the ABS/ESC module to receive two signals to verify the steering wheel’s position.