With such a priority being placed on vehicle safety, continued training on new safety technology is the cost fleets of all sizes are facing. The typical light duty vehicle has about 100 components designated to the safety system alone. Fleets are being forced to re-evaluate the level of...

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With such a priority being placed on vehicle safety, continued training on new safety technology is the cost fleets of all sizes are facing.

The typical light duty vehicle has about 100 components designated to the safety system alone. Fleets are being forced to re-evaluate the level of training their technicians have regarding airbag care.


Since 1999, the National Highway Traffic Safety Administration (NHTSA) has required frontal airbags for driver and passenger in all new light duty cars and trucks. Airbags used to be connected a sensor out on the front bumper or radiator support area, but are now multiplexed into the databus.

In 2004, 35 percent of new vehicles were required to have a more sophisticated safety system called Occupant Classification Systems in the vehicle. This number will increase to 100 percent within the next few years.

The Occupant Classification System is a sensor on the seat and/or floor that determines whether the passenger seat is occupied, as well as the weight of the occupant. With that information, the system determines whether or not it is safe, or necessary, to deploy the airbag, as well as at what power to deploy it. This system will replace the existing aftermarket switches that are used to manually turn off airbags in fleet vehicles.

According to Todd Hoffman, instructor for Inter-industry Conference on Auto Collision Repair (ICAR), while side curtain airbags are not yet mandatory, they are still a big thing for fleets.

"In most of the bigger fleet vehicles, the steering wheel position doesn't allow an airbag to be installed because the angle of the steering wheel isn't straight towards the driver. What they are doing is putting in the curtain airbags and that's to prevent injuries in roll over accidents," he says.


These days airbags are everywhere, but how often are they really being deployed in fleet vehicles?

"The airbags are being deployed quite often in smaller size light-duty fleet vehicles," Hoffman says. "An airbag deploys on deceleration. It measures the mass of the vehicle and how fast it comes to a stop."

"Fleet vehicles are loaded down with accessories. When a vehicle that has additional weight, it has more mass, and when it hits an object at a slower speed it sends a stronger signal, so the airbags will deploy faster," says Hoffman.

Minor accidents, such as hitting a curb with a fleet vehicle that is loaded down with weight, will deploy the airbag, whereas in an everyday situation where that same vehicle wasn't weighed down, it wouldn't.

"A really good example is a 200 pound occupant in a vehicle going 10 miles per hour," he says. "That's 2,000 pounds of force being driven forward when the vehicle hits a solid object. So at 10 miles per hour, that person definitely needs something to protect him. Now, if you take the vehicle itself and put a lot more weight in the back, then it will deploy the airbag at about five miles per hour," Hoffman says. "An airbag is not nearly as effective unless you have your seatbelt on."


When it comes to airbag replacement, NHTSA fills in the gaps where the Federal law gets confusing. According to Hoffman, manufacturers, distributors, dealers and motor vehicle repair businesses are prohibited by 49 U.S.C. 30122 from knowingly making inoperative any part of a device or element of design installed on or in a motor vehicle in compliance with an applicable Federal Motor Vehicle Safety Standard. However, the statute allows NHTSA to prescribe regulations to exempt a person from the "make inoperative" provision if such an exemption is consistent with safety concerns. The law also indicates you can't disable the warning light.

"The warning light has to stay functional," Hoffman explains. "If you have disconnected the airbags, and I get into the vehicle and turn the key and the light comes on, that tells me there is something wrong with that system. That way I can make the decision whether to drive the vehicle or not."

One problem with not replacing the airbag is liability after an accident. In a normal situation where someone doesn't want to replace the airbag in their vehicle, the owner of the vehicle will sign a release indicating that they are aware that the vehicle doesn't have an airbag. So if they get injured in a car accident where the airbag could have helped, no one else is liable.

In a fleet, however, "drivers of the vehicle may not have been made aware that the airbags were removed," Hoffman explains. In such a situation, a fleet driver who is seriously injured in an accident because there was no airbag in the vehicle has a strong legal case against the company because they put him in an unsafe vehicle.

"Removing safety devices knowing people could be hurt, could be criminal negligence," says Hoffman. "What happens if you disable someone's brakes and send them down the road?"

"If someone were killed as a result of safety systems being inoperable, then involuntary manslaughter or manslaughter could be brought in, depending upon the state's laws," he concludes.

The situation becomes more complicated if that vehicle ends up being resold. "There are a lot of things people are doing like taking the light bulb out or putting phony airbags in?which is really dangerous because the new owner doesn't know what's in there," Hoffman says.

There are companies that specialize in replacing airbags, and the procedures are, Hoffman says, fairly simple, so there is no good reason to sell an old vehicle without replacing the airbag.


Stephen Howe, training program development manager for Tweddle Litho Company, explains that vehicles are self-diagnosing, and technicians have been able to get body codes from the airbag control module for quite some time.

"Essentially, it's to diagnose when the lamp stays on after you turn the key," he says. "This indicates that the system is likely deactivated, because it senses an electrical problem. That way the tech knows there is an electrical problem that has to be diagnosed. It could be an open or a short."

"Now obviously, some shorts, if you create them yourself, would deploy the airbag, which is one of the safety issues. But if the system ever senses a short, it will shut itself down," Howe says.

According to Howe, items such as circuit wires, connectors, sensor failures or a problem with the squib wiring in the airbag itself could be the cause of unexpected shorts. Alternatively, there could be a short in the lamp activation circuit, so that the light is on even though there isn't a problem. Most technicians will know to use a scan tool to retrieve a body code (B-code) for body failure.

"There could be nothing wrong with the wiring," Howe says. "In the earlier systems, the sensors for the side airbags were on the floor pan. If you didn't have the bolt torqued enough, it essentially took the ground away. If you get any electrical concerns like wiring or an internal sensor problem-anything it can sense electronically-it will turn the light on and produce a trouble code," says Howe.

Howe encourages technicians to continue to read their work manuals when they are doing the initial disconnects and general inspection. "Before you even inspect wiring, inspect sensors, or disconnect any connectors, you must disconnect the battery and wait two minutes or more." The airbag systems have a capacitor in them to store battery power in case your battery line is severed during an accident; there is enough residual voltage in that capacitor to deploy the airbags.

"It takes a couple of minutes for that to drain," Howe warns, reminding technicians that the waiting time may be different for every vehicle. "Every service info section, when first opened to the airbag section, has at least two to three pages of warnings, and this information will be in among the warnings."


"The problem we are facing today is accessories that we put on the vehicle," says ICAR's Hoffman. "We're putting radios inside of a lot of fleet vehicles, we're putting hands free cell phones, and we're adding stereos systems."

Any accessory that contains a power supply, such as a cellular phone, should be treated with caution. "The cell phone is sitting there in the cradle and even though you have disconnected the vehicle battery, there's still enough voltage in that system to accidentally deploy an airbag during maintenance," Hoffman says. "Radios will have internal batteries in them. You disconnect the battery, and the airbags could still be live for two or three days."

"Whenever we wire into our electrical circuits, technicians need to be sure that they don't tap into the wire that may feed the airbag circuit," says Hoffman.

"Between lights, radios and other accessories in fleets, if you tap into this circuit, it may cause the airbag not to deploy when it is needed because you are robbing power from the circuit," Hoffman says.

"If the installers tied into the vehicle wiring and weren't careful about what wiring they tied into, add-ons and accessories could cause a problem," Howe says.

"Generally those circuits are pretty well protected, due to the nature of the systems they're on. But it is still possible to be messing around in there and short wires together and deploy the airbag," he says.

"One thing they do recommend," Howe explains, "are airbag simulators. Essentially, it's a one ohm resistor; you plug it into the connector that goes to the airbag itself. It simulates the resistance of the airbag to test the system without actually having the airbag connected.

"After disconnecting the battery and waiting for the capacitors to discharge, you would physically pull the connector off the back of the steering wheel connector that goes to the airbag and plug it into the simulator," Howe says. "That way, when you are doing a diagnostic with a scan tool or an ohmmeter, it syncs that airbag in line?at least from a resistance standpoint. That way you can test your circuits, make sure you have a good ground, and make sure you have voltage where you are supposed to have voltage."

Placement of the accessories can be just as important to the safety of the driver as the safety equipment itself.

"Where you place your radios, where you place your computers, where you place the speaker for your PA system?it's so important today that it is not in the path of the airbag," warns Hoffman.

"We're putting the radios directly above the diagnostic monitor for the airbag which is between the seats on the floor. The signal caused from static electricity or the magnetic field being transmitted from the radio could accidentally deploy the airbag," Hoffman says. "So now you've got a guy going down the highway at 60 miles an hour, he keys up the radio to call his dispatcher and it blows out the airbag."


Hoffman says the solution is as simple as putting an anti-static pad between the radio and the diagnostic monitor to block the magnetic field or static signal that is sent. Fleets can buy a rubber mat that just goes between them to block the signal. "I think it is something they don't have a clue about," Hoffman says.


"In my mind, you should NEVER put a vehicle back into service that does not have the full compliment of safety equipment, including all airbags and seat belt pretensioners," recommends Howe.

"If you are already performing body repairs on a crashed vehicle (or sending this out to a body shop), the cost of the airbag is relatively insignificant versus the body repairs. Most important, the lack of an airbag compromises the safety of the driver and occupants," he says.

"Also, you're going to create trouble codes unless you do some serious reprogramming to the vehicle electronics. The labor involved in the reprogramming would likely cancel out any cost savings for not replacing the airbag. While the airbag deployment circuits remain stand-alone (for safety reasons), the occupant restraint controller (ORC) and occupant classification module (OCM) do share data with the instrument cluster and other vehicle modules," Howe says. "Airbags are part of a system. By disabling a part of that system, it could affect all other safety devices in the vehicle," warns Hoffman.

"There is really a lack of training when it comes to why airbags and seatbelts work together," Hoffman says. "Location of accessories, clearing the path of the airbag-all of these combined could not only save fleets money, but could also save lives."