Airbag Switches for Law Enforcement
Airbag Switches for Safety - Police Vehicles



The following points are intended to help explain the specifications. 

Multistage airbag switches

Multistage airbags, as used in many cars built for model year 2001 and later, including Crown Victorias and Impalas, require multistage airbag switches in order to simultaneously turn both of the airbag’s stages (detonating circuits) on or off.

The idea of the removable key is a federal requirement and insures that only the person possessing the key controls the switch.

One Yellow Indicator Light

NHTSA only requires only one light (yellow) to indicate when the airbag is turned Off.

More than one light can be confusing, especially to anyone who is color-blind.  If there is more than one light, it becomes a matter of telling colors apart. This is especially difficult for most color-blind people when the lights are green and yellow, and is even more difficult in the dark

If there is only one indicator light on the switch, it indicates conclusively that the airbag is OFF, even in the dark and even if the operator is color-blind. (When the airbag is on, there is no light on the switch.) Therefore one light on the switch is far better and less confusing than two lights. 

   
 Internal Fuses

Unlike Airbag Switches by Sensible Solutions, some switches contain an internal fuse.  The idea is to protect the manufacturer from liability in case someone claims the airbag switch was turned off but the airbag deployed. The purpose of the fuse is to provide evidence of a switch’s position when a detonation impulse is received from the vehicle’s airbag controller.There are two problems with this.

bulletFirst, the switch will no longer perform its function once the fuse opens. This means the SRS light on the instrument panel will stay on when the airbag switch is turned to the airbag OFF position until the fuse is replaced. When a fuse is hardwired into the switch internally, the switch must be replaced.  Until the switch is replaced, there is no way to tell if there is another problem in the SRS system when the airbag is turned off. This means that if the airbag switch contains an internal, hardwired fuse the vehicle must be taken out of service until a replacement switch is installed in order to meet federal requirements. Many departments have difficulty when their cruisers are unexpectedly out of service. This is why the specification requires the manufacturer to certify that the switch will continue to work and satisfy federal requirements until a replacement switch can be installed. Without a fuse, this is not a problem. 
bulletSecond, the fuse will not conclusively resolve the question of the switch's position during an accident. Any litigation attorney will be quick to point out that the driver may not have noticed the instrument panel light before the accident, so the fuse could have opened any time.  On the other hand, after an airbag deploys, a simple electronic test can conclusively prove a switch’s position at the time of an accident, so a fuse is not necessary.

Having a fuse will force the owner to replace switches periodically. For this reason, the spec requires the manufacturer or provider to replace switches with opened fuses at no cost to the owner for a period of ten years. (Alternatively, the spec could state that there shall be no internal fuses). Sensible Solutions can provide switches with an optional external fuse if this is requested, but once this issue is understood we have never had a request for a fuse.

Gold Contacts  

 This is an important advantage because gold doesn't corrode, and the switches will last far longer than non-gold contacts. Other metals are used in switches when the current is high enough to insure that the contacts clean themselves when the switch is moved from one position to another. Usually this contact cleaning requires at least 25 Milliamps in the switched circuit. But in an airbag circuit, the current is well below 3 milliAmps, so corrosion of the internal switch contacts is inevitable. This is well known to engineers in the electronics industry, and is why they use gold contacts in low current applications. In the Auto industry, gold contacts have been required on low current electronic circuits since WW2. 

An airbag switch that doesn't use gold contacts will eventually fail because the buildup of internal corrosion on the internal contacts will add too much resistance into the airbag circuit. The only remedy then is to replace the airbag switch.

The method of soldering used is critical when dealing with gold contacts. Too much heat and the life of the switch will be significantly less because the gold melts off the metal substrate of the contacts. Controlling the solder temperature and exposure time is reliable only when soldering is performed with programmable computer-controlled soldering equipment. Our switches are made using state of the art equipment, including Wave Soldering of the circuit boards.

The auto industry uses the SAE (Society of Automotive Engineers) specifications for in vehicle systems that transmit data which also require gold contacts on electronic connectors. These are covered under SAE AS 39029 and SAE/UCAR-2-4 Rev3. Sensible Solutions airbag switches use gold contacts.

RF Filter built into switch circuit

Each airbag switch has our internal filtering circuit (patent pending) to remove Radio Frequencies (RF) from the circuit and eliminate the possiblity of accidental airbag detonation because of inductive reactance.

There are numerous frequencies in the radio spectrum reserved for police, government and emergency use. These frequencies include the ones police cruisers, fire and emergency vehicles use for communication. The problem is that without a filter, any wire can pick up radio waves just like an antenna. Depending on the frequency and the length of the wire itself these radio waves can create a current in the airbag switch wire.  An airbag circuit, requires very little current to detonate an airbag. These RF waves can produce a detonating current unless they are filtered out.

Sensible Solutions is the only airbag switch manufacturer that uses an internal filter circuit to remove any RF induced currents, so these switches will not induce accidental detonation, especially from transmitting radio frequencies.

 If you have any questions about the specifications, or want to discuss these points, please call the Chief Engineer at Sensible Solutions LLC at 301-473-7908 or 877-773-7908.

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