Do Brush Guards hinder Airbag Sensors?

[Luxury]

I have been asking around and have finally gotten a few responses. I figured I would start a new thread dedicated to the topic to try to summarize and also generate further discussion. Has anyone else looked into if the airbag sensors are hindered by any type of brush guard?

I emailed Tal & Hadas (the brush guard I am most interested in) and received the following response:

>>> <[email protected]> 8/10/2004 5:24:52 AM >>>
Hello Jason:
Regarding your questions, To date we have not conducted any air bag testing. Please consult your vehicles manufacturer for installation of aftermarket off road equipment.

Thank you,
Hugo Baeza
North American Division Manager
314 24th Street
Brooklyn, NY 11232
Toll Free: 1-888-294-5907 Local: (718) 832-6720 Fax: (718) 832-6730
Email: [email protected] Website: _www.THoffroad.com_
(http://www.thoffroad.com/)

 

[Luxury]

Here are some of the other discussions from other threads:

From this thread: http://www.toyota-4runner.org/showthread.php?s=&postid=36643#post36643

...... My main concern is about them affecting the airbag sensors. I couldn't find anything about the subject here on T4R.ORG but did find a small discussion of it on edmunds:
http://townhall-talk.edmunds.com/We....ef15c89/511!keywords=allin:msgtext guard bag
Does anyone know if the Tal & Hadas or other guards affect the airbags?

From this thread: http://www.toyota-4runner.org/showthread.php?s=&postid=40442#post40442

quote haps:
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do the grille guards cause to the actual functioning of my airbags?
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quote CMiYC:
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None. The airbag sensors are decelerometers. Nothing about a grille guard will interfere with them. In the first generation, the sensors weren't even placed in the front of the car.
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Does that pertain to all generations?

......RE: Airbags: from the WAAG Site:

<B>Do you have any information on how grille guards affect deployment of air bags?</B>

<I>There is no conclusive or comprehensive data at this time regarding air bags deployment and opinions vary to say the least. Some vehicle manufacturers, most notably Ford, Nissan and GM offer a factory grille guard for some of their trucks, so you may be able to draw your own conclusions from that. We consider our guard a medium-strength guard, suitable for pushing a vehicle, but one that will crush in an accident.</I>.......

 

[Luxury]

I just did a search (apparently with better terms than before) and found another thread.

From this thread:
http://www.toyota-4runner.org/showthread.php?s=&threadid=1603&highlight=guard+airbag

.....Also, I have a silly question. I would love to have light/push bar on the front of a 4Runner (when I purchase one), would that effect the air bag sensors in a front crash?....

you'll want to get another opinion, as i don't have a new 4runner with air bags, but i'm pretty sure that the sensors in the 4runner (and most new vehicles) are deceleration sensors rather than impact sensors. so you should be able to get away with putting something on your bumper. even if it is a impact sensor, i don't think it will be a big deal if you put something on there. if it's a small enough accident to not set off the sensors, then you don't want the airbags going off, if it's a big accident, then the light bar isn't going to do much anyway.

Yes, most new vehicles have "decellerometers" for airbag ignition. The problem with impact sensors like "first generation airbags" was that airbags would go off in very minor fender benders.

The front brush guards, light bars, etc won't affect the airbags. I don't like them, but you can use them. In fact some brush guard makers advertise they are "airbag compatible". Really, if you stuck a bicycle on the front it would be "airbag compatible".

 

[CMiYC]

You've already answered your own question. Airbag sensors are decelerameters and not impact sensors. Nothing you put on the front of the car will affect them. If it did, cars wouldn't have bumpers.

Grille guard manufactuers aren't always willing to say they don't affect them. Too many people don't understand how airbags work or what their purpose is. So its easier to say "we don't know" than have an idiot sue them.

A huge misconception is that the sensors somehow detect the amount of damage to your car before deploying. They simply detect when your forward velocity suddenly becomes 0. Have you ever heard someone say "I don't know why my airbag didn't deploy, I hit the pole!"? Well if the hit the pole after slowly down enough, it wouldn't deploy.

On the 4th gen 4runner, you can see the sensors when the hood is open. Just look straight down. If I recall there are two of them. My guess would be there are multiple sensors on something like the 4runner to better detect the vechile's momentum.

 

[Luxury]

I know I answered my own question, based on the previous posts. I guess I was mainly interested if someone had confirmed this with Toyota or had some sort of reference. I know I am probably worrying too much about the issue. It's partly because the purchase of brush guards can get pretty pricey and I don't want to purchase one, only to find out later that it is causing a greater risk to my life. Plus, I wasn't sure if this sensor design was employeed in every generation of 4runner. At least this will serve as a summary and a thread for future input.

 

[Luxury]

This article on MEMS (Micro-Electro-Mechanical Systems) talks about airbag sensor design.

http://www.cooksonsemi.com

Air Bag Electronics:
We’ll begin with the accelerometer, one of the earliest and most important MEMS devices. The chiptypically uses a cantilevered silicon arm or a combthat bends slightly when there is a change in motion. Movement is detected and translated into an electricalresponse. Analog Devices, a leader in this field, usesa design where a movable beam and a stationary oneform a capacitor. Motion changes the spacing andthus the capacitance to translate deceleration into anelectrical signal. The system must accurately sensedeceleration and send the signal that deploys yourairbag. The deployment signal must only triggerunder crash conditions. “Almost right” is not goodenough in a life and death situation as has beenshown in some unfortunate incidents. The packagedproduct can appear very ordinary since traditionalmethods can be used here. This is one of the fewMEMS products that can be completely sealed since motion detection does not require an opening to theoutside. Still, the packaging cannot interfere withmechanical movement and must have low stress.Package stress, if present, must be predictable so thatallowances can be made. The critical factor for boththe packaging and assembly is stress. Anything thatincreases package stress will change sensitivity.The accelerometer (decelerometer) must sensechange in motion but not in all directions. The sensormust detect the rate of change primarily in theforward direction of the vehicle. We don’t want theair bag activated if the vehicle is rear-ended or hitfrom the side or bounced by a pothole. Some cars areadding side air bags, but their separate sensors detectside-ways motion. Anything that interferes withsensing the direction or alters the ability to detectabsolute deceleration will be a problem.

 

[dancojgl]

The addition of a brush guard (or snow-plow, push bar, etc.) mounted to the frame may, if anything, increase the chance of air bag deployment, rather than decrease it.

This is because a rigid brush guard, rigidly connected to the vehicle frame will bypass the bumper and front crumple zones. The bumper and front crumple zones absorb some impact energy and reduce the deceleration rate of the vehicle behind these structures.

With these structures bypassed and an impact on the brush guard transmitted dirctly to the frame, the air bag decelerometers will sense a higher deceleration rate.

Is this decrease in sensitivity significant, or even measurable? I don't know. But at least with this mod you're changing the safety margin in the conservative direction.

OTOH, if you don't run into anything, you'll be fine...

—Dan

 

[Good Times]

just to throw a bone out there...

them brush guards do absolutely no protection on frontal collisions. they're known to do more damage to your own vehicle. keep that in mind.

as for the airbags, need not worry, anything you throw up front won't affect your airbags. the only thing it might do is make the sensors abit more sensitive due to the fact that the brush guards is not able to take the impact as well as the plastic tupperware bumpers.

i on the other hand have a custom steel bumper so the crumple zone concept is out of the question. o well i guess.. atleast whoever I hit or get hit will be in.... you get my point.

 

[Luxury]

ANOTHER new thread brought up this topic:

........I asked a bunch of questions, one of which was in regards to a full front bar. Well, to my supprize, Toyota does not recommend, does not carry, sell and install them at all. Since it attaches to the frame of the truck, they will not guaratnee your safty, that is your aribags, bumper, sensors etc. It does make sense when you think about it, but you see so many trucks with bars that it doesn't even cross your mind.

As to the welcome sesstion, there were few "elite" technicians and a couple of cars (of course no 4runners). When I asked them more specific questions (about 4wd, hitch etc) they didn't know much..............