weight controlled passenger airbag

tzuraw · **Joined:** Tue Oct 10, 2006 12:52 pm **Posts:** 18

Does anyone know if it is easy to disable the weight sensor on the passengers seat? The reason I want to do this is that when my wife sits in the seat it disables the airbag, she is about 110lbs, we have no children, dealer said she is right at the cut off point. If I get in an accident I want her air bag to deploy.

sleeve84028 · **Posted:** Wed Oct 25, 2006 1:43 pm

OCS = Occupent classification system

There is a sensor on the seat cushion, therefore there is a wire leading up to the sensor that has to have a quick disconnect on it. I don't know if unhooking the sensor will activate the airbag though? It might throw a code or disable the entire system? I am not sure since I don't have it in the '02.

100+ pounds seems high for a cutoff though. You would think it should be around 90...

dog_party · **Posted:** Wed Oct 25, 2006 1:44 pm

Wow! 110 is the cutoff?! That's crazy! I heard it was 75lbs.

2006KJSPORT4x4 · **Posted:** Wed Oct 25, 2006 1:53 pm

I believe the cutoff is less then 75 lbs...but check the owner's manual there might be an easier over ride then having to pull some wires and making a wrong pull...."blue wire, no red wire....BANG!!!!!"

Elwenil · **Posted:** Wed Oct 25, 2006 1:58 pm

The whole point in the classification system is to prevent someone who has less body mass from being injured by the airbag. In the case of a person with a low body mass, as with my girlfriend also, they are better off not having the airbag deploy as it will strike them with enough force to cause possible neck injuries or similar. The airbag is designed to slow down the forward motion of your body in an impact crash, not be a inflatable pillow to land on. Leave the airbag system alone. In many cases it is illegal to tamper with the system.

Jeepjeepster · **Posted:** Wed Oct 25, 2006 2:33 pm

She may weigh 110 pounds, but how much of that mass is in her legs. Remember, the are resting on the floor which takes some of her weigh away. I bet if she picked her legs up the light would go off..

If she doesnt weigh enough then she doesnt need the airbag. Like Elwenil said, its to slow down the body during a head on crash.. If she doesnt weigh enough then she could be hurt by the airbag...

The sensor also controls the rate at which the bag deploys. Depending on the seat position and the weight of the person, it will deploy faster or slower.. :wink:

Jeger · **Posted:** Wed Oct 25, 2006 2:53 pm

Jeepjeepster wrote:

She may weigh 110 pounds, but how much of that mass is in her legs. Remember, the are resting on the floor which takes some of her weigh away. I bet if she picked her legs up the light would go off..

If she doesnt weigh enough then she doesnt need the airbag. Like Elwenil said, its to slow down the body during a head on crash.. If she doesnt weigh enough then she could be hurt by the airbag...

The sensor also controls the rate at which the bag deploys. Depending on the seat position and the weight of the person, it will deploy faster or slower.. :wink:

Along the same lines as jeepster....

It may not be completely shutting the airbag off, I believe the sensor does more than just turn it on or off, could just be at the right weight to put it into a reduced force mode

Elwenil · **Posted:** Wed Oct 25, 2006 3:12 pm

I believe it does indeed disable the airbag completely when the light is illuminated. If I remember right, the seat belt retractors and such work normally though.

Elwenil · **Posted:** Wed Oct 25, 2006 3:21 pm

From the 2006 Jeep Liberty Service Manual:

Quote:

Pre-programmed decision algorithms and OCS (Occupant Classification System) calibration allow the OCM microprocessor to determine when passenger airbag protection is appropriate based upon the seat cushion load as signaled by the bladder pressure sensor and the seat belt cinch load as signaled by the belt tension sensor. When the programmed conditions are met, the OCM sends the proper electronic occupant classification messages over the PCI data bus to the Airbag Control Module (ACM) (also known as the Occupant Restraint Controller/ORC), and the ACM enables or disables the deployment circuits for the passenger front supplemental restraints. The ACM also provides a control output for the passenger airbag on/off indicator in the instrument panel grab handle based upon the electronic occupant classification messages it receives from the OCM.

sleeve84028 · **Posted:** Wed Oct 25, 2006 3:21 pm

When the light PAB (Passenger Air Bag) is illuminated - the ignitors for the bag are not active.

Seat position is not part of the calculation for airbag speed. Only weight and seatbelt information. All seat positions are tested in pre-development of the restraint systems restraint systems include: seatbelts, knee blocker / glove box and air bag. When an accident occurs, the 5th %-tile female tends to hit lower on the plastic and slide under things. While the 95th 5-tile male tends to just run right into the insturment panel. Cars sold after 2008 will need to protect people in: offset angular crashes of 35MPH, unbelted 25MPH hits and belted 45MPH hits.

FMVSS information should be online

tzuraw · **Joined:** Tue Oct 10, 2006 12:52 pm **Posts:** 18

I can understand how it may be better in some situations to not have the bag fire, but in all my other cars the air bag had no weight requirment. CAn they not design a bag that will work with different weights? I would think it would be better to get hit a little harder by an airbag, then to hit the plastic dashboard with my face. So basically I am riding my wife around in a car that only has 1 driver side airbag. THAT IS LAME. It is a 2004, I would think it would have side impact airbag also.

I orginally thought the idea was not to deploy the airbag if no one is in the seat, to save money when having to repair, one airbag verse 2 airbags, but I guess that is not the case. This seems very odd to me, my last car was a VW beetle and it had 4 airbags, none were weight dependent.

Elwenil · **Posted:** Thu Oct 26, 2006 1:34 pm

I don't think you understand how powerful these things are. When we replace them we generally take some pretty big precautions to avoid spiking the system and setting them off accidentally. Even after everything is hooked up the Service Manuals normally say to lay in the passenger side floor board and reach over to turn the ignition on the first time. If one of these things would go off in your face without you having some serious momentum pushing you into it, it would hit you in the face like a train. I'm talking broke neck, paralyzed for life, Christopher Reeve sort of thing here. Same deal with a person with little weight to themselves. The airbag would knock the hell out of them. Older vehicles did not have this system, and it was the resulting injuries that prompted people to believe that they were more harm than good. Then they came out with the key switch to disable the passenger side bag for car seats or light passengers. Since most sheeple, given the choice, will make the wrong decision this system was designed to take out the guesswork.

dog_party · **Posted:** Thu Oct 26, 2006 1:37 pm

In this case, deactivating the passenger airbag is not about saving the replacemement money of a depolyed airbag. When there's no one in the seat the airbag is deactivated for that reason. But when there's someone "under weight" in the seat it's the "smart" tech that deactivates it because "it has been found" that hitting a deploying airbag actually does more damage to smaller people that hitting face-to-dashboard. When a shorter (assumedly lighter weight) person sits in the front seat and hits a deploying airbag, they have been found to fold in half (the person, not the airbag). The lap is restrained by the lap belt, but then (when you're shorter) enough of your body mass is below the center-line of the deploying air bag that your torso tries to go under the bag. If you lean forward in your chair (keep your rear against the seat-back like your lapbelt is on) and then, in the middle of the lean-foward motion, pull your head back (look up). You'll start to understand why a deploying airbag that's averaged for someone that is 5'7" (I think that's the airbag average) might not be really safe for someone that's quite a bit shorter.

The assumptions/averages are based on the idea that taller people are heavier. So a light-weight person is assumed to be short. This is not always the case, but it the easiest way to automate the process of not folding children in half. If it weren't for that, we'd have the key-hole in the dashboard (like they have in a lot of full-size trucks).

I'm not trying to support or attack the method of automated air-bag deactivation deployment. Just spouting the worthless trivial information that has been cramed into my head by the overwhelming lack of silence that pervades life as I know it.

ATXKJ · **Posted:** Thu Oct 26, 2006 1:47 pm

Airbags are inflated by an explosive, there have been people killed by the bag itself - statistically it's less than would have been killed by the collision. This was a good explaination of the Physics.

http://www.chemistry.wustl.edu/~edudev/LabTutorials/Airbags/airbags.html

sleeve84028 · **Posted:** Thu Oct 26, 2006 2:06 pm

I am a R&D engineer for a supplier to DCX. I know all about airbag systems (if you were refering to me) I work to position them properly than then test-fire them during development. I've seen plenty of stuff to make your stomach turn... Trust me you don't want to see the early development videos for the Liberty.

But I think we all agree to leave the programing and systems alone and let the computer decide the correct course of action.

Elwenil · **Posted:** Thu Oct 26, 2006 2:16 pm

Sleeve, I agree with you completely, my comment, if I am who you were speaking of, was directed to Tzuraw whom I didn't think had a clear idea of the operation of the system or the physics involved. Between all of us I think we have the bases pretty well covered on this topic, lol. :lol:

hallb4 · **Posted:** Thu Oct 26, 2006 2:28 pm

Install a race car seat belt with that straps over your shoulders!

sleeve84028 · **Posted:** Thu Oct 26, 2006 2:52 pm

I see.. Just wanted to make sure..

The only time you should use a racing style 5-point harness is when you have a roll bar / cage installed to mount it to. They are very effective, but also very constraining so it makes grabbing for your drink a little difficult.

dog_party · **Posted:** Thu Oct 26, 2006 3:04 pm

sleeve84028 wrote:

I am a R&D engineer for a supplier to DCX. I know all about airbag systems (if you were refering to me) I work to position them properly than then test-fire them during development.

I'm not sure which post you were referring to Sleeve. But, I wasn't speaking specifically to anyone, just passing along the information that's been delivered to my brain as "knowledge." I thought it should be mentioned that there are two main reasons for disarming the airbag. 1. saving your insurance company (read: making your insurance company MORE money), and 2. saving smaller-than-average people from being injured by the deployment of an explosive "air"-filled bag that is made/set for an average-height adult. Can you shed some light on the averages used in placement?

sleeve84028 wrote:

I've seen plenty of stuff to make your stomach turn... Trust me you don't want to see the early development videos for the Liberty.

OhhhhHHHHHhhhh yes I do.

Yes ineedy!

sleeve84028 wrote:

But I think we all agree to leave the programing and systems alone and let the computer decide the correct course of action.

I would only disable the automated safety system if the vehicle was equipped with a roll-cage and 5-point harnesses on each occupied seat. And, since I don't plan to add those to my KJ anytime soon, YES, I agree to leave it alone.

I do, however, have alternate plans for our 99 Miata. That little skateboard could really use a rollcage and racing seats

and maybe a few hundred laps around VIR.

sleeve84028 · **Posted:** Thu Oct 26, 2006 4:13 pm

I'll see if I can find the video of the door flying open and the crash dummy hitting the sun-roof. that one is pretty fun to watch

weight controlled passenger airbag

Who is online