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Proactive National Car Care Month Plan Could Lead To More Business

As gas prices continue to drop, ­consumers will have a few more dollars in their pockets to spend on essentials, like vehicle repair and service. Getting customers to spend some of those dollars in your shop should be one of your goals this spring. With...

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Do Training, Technology And Parts Sourcing Issues Keep You Up At Night?

We often hear that the things that keep shop owners awake at night pertain to profitability, productivity, training, keeping up with technology, shop operations/expenses and parts quality/availability. This month, we hear directly from one of your...

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Top 10 Automotive Repair Shop Pet Peeves

No two days are the same for the owner of a repair shop. Every day brings its unique set of challenges to overcome, but, for the most part, the day progresses along and one day passes to the next. But, there are those occasions when certain daily activities...

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Engine Coolant Temperature Diagnostics

While old-school cooling system service often ­focused on coolant leaks and overheating engines, let’s begin thinking “new-school” by looking at modern cooling systems through the eyes of the engine coolant temperature (ECT) sensor. Coolant temperature...

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Volkswagen: Parking Indicator Sounds Off with No Obstacle

Customer complains that the parking assistance issues warning sounds for both the front and/or rear of vehicle with no obstacle in range. Water intrusion into sensor holders is causing corroded plug contacts and sensor electrical pins, which results in...

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Volkswagen: Unnecessary Electric Coolant Fan Replacements

Model: 2006 Volkswagen Jetta Sedan Customer concerns of “electric coolant fans continue to run after the ignition is switched off” are resulting in unnecessary coolant fan replacements. It is considered normal operation for the electric coolant...

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Weak Air Ride Compressor Diagnostics

Air ride systems always used to have two diagnostic paths: either the vehicle was riding low or the compressor blew a fuse. Today’s modern vehicles have computer-controlled air ride units at all four corners that can pose a unique diagnostic challenge...

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Ford Fusion Alignment Spec (2005-‘13)

Millions of Ford ­Fusions were sold in the U.S. between 2005 and 2013. When it comes to alignments, it is critical to diagnose the customer first, to find out if their Fusion drifts or pulls, and then to check all of the possibilities for the complaint...

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Nissan Titan Brake Job

The Titan is Nissan’s full-size pickup. The Titan has had no major brake problems or recalls, and the brakes are fairly easy to service. Nissan had a few teething problems with brake judder on 2004-‘06 models, but this was corrected with better...

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Know the Specs for Your Social Media Accounts

By now, we should be well past the things I heard as recently as two years ago: “Social media is just a fad,” “No one will follow a (repair) shop on Facebook” and “I don’t care what you had for dinner, and I’m sure you don’t care where...

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MAHLE Service Solutions' New R1234yf Recovery Machine Named 'Best Use Of Technology' At MACS 2015

The ArcticPRO ACX1280 machine from MAHLE Service Solutions received the “Best Use of Technology” new product award at the 2015 Mobile Air Conditioning Society (MACS) Worldwide Trade Show. The award was selected by an impartial panel of automotive...

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Bartec Updates Tool Software

Bartec USA released its next tool software update for its range of TPMS tools. This latest tool software release integrates TIA’s TPMS Relearn Chart into Bartec’s TMPS software. “The TIA Chart is a must-have for any back shop whether general...

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Home Electrical Battery Air Ride: Compressor Diagnostics

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On most modern vehicles, the compressor and air ride control unit are very intelligent components. Most communicate with the Body Control Module (BCM) on a high-speed serial data bus. These systems have malfunction indicator lights on the dash and require the use of a scan tool to diagnose the system. 
 
Servicing modern air ride systems requires the right service information to interpret the “C” or chassis codes the air ride system can generate. A failure code and an illuminated dash light could be just a failure of the air ride module to communicate with the BCM. This could be due to electrical problems and not a leak in the air system or a compressor failure. 
 

With an enhanced or factory scan tool, it is possible to perform bi-direction tests on the compressor and valves during inspection. This can save you hours of diagnostic time waiting for a compressor to turn on and drain the battery or testing for an intermittent condition. Throwing parts at these vehicles without performing a proper diagnosis can result in an unhappy customer and lost productivity.  
 
The air ride module does more than control the ride height. The software controls the temperature of the compressor so it does not damage itself trying to inflate a leaking air bag. It can also change the characteristics of the air bag in response to how fast the vehicle is going and if it is in sport or towing mode. But most of all, it helps to filter out erroneous ride height readings so the best possible ride is achieved.  
  
Compressor Killers
Most passenger and light-truck compressors are diaphragm types that supply an oil-free air supply to the springs. A piston-type compressor can be found on applications that require a higher volume of air. 
 
Running the compressor for extended periods can over heat the compressor and damage the diaphragm or piston. It is very important to ensure that the source of air for the compressor is clean and as dry as possible.
 
In the air is moisture that can damage not only the compressor, but the valves. When air is compressed, the water vapor contained in the air is condensed into a liquid. If there is no means of removing the water from the system, it will find its way to all parts of the system causing corrosion damage or freezing.
 
Most systems have a dryer that is connected to the compressor outlet to absorb the water entering the system. The dryer contains a moisture-absorbing desiccant such as silica gel. The desiccant can hold a given amount of water and once the desiccant is saturated with water, it will allow water to pass into the system.
 
The dryers that are installed on most systems do not have an indicator that will show when it is saturated and no longer able to absorb water. An additional dryer with a moisture indicator can be added to the original equipment dryer. It can be installed in the supply line and placed in a position where a periodic check can be made.
 
Some systems have filters on the air intake for the pump. The filter removes airborne particles and acts as a noise muffler for the compressor. Some systems even send purged air back through the filter. This filter should be replaced with the compressor, and often this filter is attached to the compressor’s casing. 
 
Another killer of air-ride components is the compressor. As the compressor over heats and wears, it can send debris and oil to the rest of the system. This oil and debris can degrade the air bellows even after the compressor is replaced. This is why it is critical to flush the lines if a compressor has failed.  
 
Some systems have air reserve tanks or accumulators located in the most inconvenient locations, like below the C-pillar or next to the frame rail. If the system experiences a catastrophic failure of the compressor or air bladder, replacement or flushing of the reserve might be required.    
The health of the entire system depends on the quality of the air supply. It is rare for just one component of an air suspension to fail.  
Mechanical and Solenoid Valves
There are various combinations of both mechanical and solenoid valves.

The function of the mechanical or solenoid valve is to exhaust air from the spring(s). Each spring can have a valve. For the Lincoln air suspension system, there are five solenoid valves — one for each air spring or strut and one to exhaust air from the system. 
 
Most valves are used for a pair of load-assist springs. The compressor unit contains a one-way check valve to isolate it from the springs or a reservoir. The Lincoln compressor has a combination one-way check valve and exhaust solenoid valve to inflate or exhaust the springs individually. Whether the valve is mechanical or solenoid, it needs dry air to operate properly.
 
Plastic line is used to transport air in the system in sizes 1/4”, 3/8” and 1/2”. Most fittings are push-on O-ring type ranging in size from 1/8” to 3/8” Male NPT.
 
Air struts for some import vehicles can have even more complex valves, air chambers and accumulators on the strut body to keep the suspension taut under certain conditions. These types of struts will have both an air and electrical connection to control the valves on the strut and the hydraulic valves of the dampener.  
Dynamic Vehicle Trim
The Lincoln Continental Mark VIII is equipped with ride height sensors at each front wheel and one for the live rear axle at the driver’s side control arm. The sensors provide input to the controller for ride height. The suspension controller is programmed for two different ride heights.
 
Parked, the vehicle will maintain this height by compensating for passengers and luggage. When the vehicle is put into gear, the controller will raise the suspension ride height 0.75 inch (20 mm). When vehicle speed exceeds 63 mph (105 kph), ride height is lowered by 0.75 inch (20 mm). When vehicle speed decreases to 45 mph (72 kph), the vehicle ride height is increased. The differential between 45 and 63 mph provides a dead band where the system will not adjust ride height. This prevents the system from cycling with small changes in vehicle speed. With the ignition off and doors closed, the vehicle returns to parked height.
 
The rear air struts on GM vehicles are used to assist the conventional coil springs. Cadillac vehicles with Road Sensing Suspension (RSS) have an electrically operated hydraulic valve located at the base of the air shock. There are sensors located at each wheel that supply input to the ride controller that operates the valves in the air shock and front struts. The suspension height sensor is located on the driver-side control arm and the compressor is located in the rear suspension cradle.
Alternatives
There are suppliers that can provide economical replacements for both springs and struts. These alternatives replace the air ride components with springs and conventional ride control units. On some vehicles that still have 100,000 of miles of useable service left, these kits can offer an economical option for the driver. Also, some remanufacturers are willing to pay for the worn air ride shock or strut cores that come off the vehicle. In some cases, the core could be worth $300! 
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Andrew Markel

Andrew Markel

Andrew Markel is the editor of Brake & Front End and Servicio Automotriz magazines. He has been with Babcox Media for more than 12 years. He is a technician and former service writer and holds several automotive certifications from ASE and ­aftermarket manufacturers. He can be reached at amarkel@babcox.com.
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