Pulling Stumps=deployed airbags

dave_mcmillan

New member
Let me start as saying this was not expected and I wish I had a Mulligan.
I was helping a friend cut down some trees. All went well with this and we began the removal of the stumps. After successfully pulling up 1 stump (8" in diameter). I began on the 2nd (10" diameter). After the first pull the 2nd and larger stump budged so I gave it a little more acceleration and WHAM!!! both air bags deployed and the horn was singing. As an added side effect when the passenger air bag cover hit the windsheild it broke. I can see a shatter line on the windshield where the passenger cover hit which surpises me that plastic would break a windshield. :ybrick:

I was not hurt in this ordeal neither was the truck all other functions work fine (transmission etc....) other than the horn. I Started thinking this may have inadvertly answered the age old question about how do after market bumpers affect airbags. Since I was pulling from my trailer hitch (factory) I was really confused as to how the air bags wound up being deployed. After speaking with my neighbor who was a Toyota mechanic he expalined the Airbag sensor is not in the front of the vehicle (bumpers etc) but rather it is a module controlled event with the module being mounted somewhere near the center of the vehicle most likely around the transmission. Still doing the research as to where exactly this is located.

If you want to disable your airbags pull fuse #7 on your fusebox in the engine bay this will disable the airbags and emergency flashers. In retrospec this would have been good to know and would be saving me from having to repair the truck.

Other than the now really good story to share I am opening the question is there anything that I should look at other than fuses etc and trailer hitch mounting location to inspect for damage?
 
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When you say WHAM, can you describe that a little more? Did you accelerate with no tension on the rope/chain/whatever and then experience a violent sudden stop?
 
Sudden stop from the Chain being pulled tight...basically I backed up about 2-3 ft and gave it a little gas (L or first gear on my automatic) then let the chain "shock" the stump. Yeah I know seemed like a good idea at the time...
 
Yep, 3rd gen air bag accelerometers are below the stereo, near the shift levers. Sorry to hear of the mishap, Dave. As you've found, these aren't really stump pullin' trucks! :-)
 
Good to know but I am surprised though, I knew that sensors are activated by deceleration forces, but I thought the vehicle needed to be traveling at a certain speed too.
 
Good to know but I am surprised though, I knew that sensors are activated by deceleration forces, but I thought the vehicle needed to be traveling at a certain speed too.

If they only went off at a certain speed then if you were rear ended while sitting at a red light, your airbags wouldn't go off...
 
Yeah, shocking your vehicle like that is a really bad idea, not just for the airbag deployment, but because it can do damage to things you might not expect and cause latent failures later.

As far as the windshield breaking, that is fairly expected. Many airbag systems actually use the windshield to help direct the airbag into the right place. It is important that the windshield not completely blow out. Shatterproof glass technology has allowed this functionality.

The airbags need to go off if you get plowed while at a light.
 
Im almost positive the air bag sensors are in the front of the engine bay, there is one on each side. One under the air box and one under the battery. Are they something else if the accelerometer is in the dash??
 
ive done some pretty extreme snatching (with chains - and NO i dont do that anymore - learned after chain broke . . .. ) but mine never went off. and i slid into snow bank pretty hard last winter (pretty much straight into it at a decent speed) and nothing went off.

that is some scary stuff dude.
 
ive done some pretty extreme snatching (with chains - and NO i dont do that anymore - learned after chain broke . . .. ) but mine never went off. and i slid into snow bank pretty hard last winter (pretty much straight into it at a decent speed) and nothing went off.

that is some scary stuff dude.

You have to understand the rapidity of the acceleration / deceleration. Hitting a snowbank probably provides enough of a "buffer" that your deceleration wasn't nearly as steep a slope as getting hit while stopped or running into a relatively immovable object.

Also note that it's primarily only detecting front-to-back acceleration/deceleration. Getting hit sideways will not deploy your airbags.

My first 4Runner was totaled when it hit a tree (I was not the one driving it), but the airbags did not deploy even though the driver hit the windshield.

IMG_2212.jpg~original
 
when i say snatched by chains, i mean it. i got really, really, really, stuck after i first bought the 4runner 4 yrs ago and had to find someone to pull me out. i was pulled out in reverse (only option). dude was in a newer F150 4x4 and we had a longggggg chain (ONLY THING AVAIL). anyways, i thought my sht was about to get ripped in half. snatched was so intense ive wondered to this day what it really did to the ole 4runner. i mean, pulled so hard back tires came off ground over a small dirt mound. it was a dumb, dumb, DUMB thing for me to do, and cant say Ive done anything that stupid since. i guess short version of the point: airbags didnt go off, and im sure that i had a good deal of force goin on with that maneuver.
 
when i say snatched by chains, i mean it. i got really, really, really, stuck after i first bought the 4runner 4 yrs ago and had to find someone to pull me out. i was pulled out in reverse (only option). dude was in a newer F150 4x4 and we had a longggggg chain (ONLY THING AVAIL). anyways, i thought my sht was about to get ripped in half. snatched was so intense ive wondered to this day what it really did to the ole 4runner. i mean, pulled so hard back tires came off ground over a small dirt mound. it was a dumb, dumb, DUMB thing for me to do, and cant say Ive done anything that stupid since. i guess short version of the point: airbags didnt go off, and im sure that i had a good deal of force goin on with that maneuver.

I agree that seems like a situation that would have made them go off. I guess the circumstances have to be just right. Still seems crazy to me. Like there was a malfunction of the OPs airbags. I agree that they need to go off if rear ended at a light or similar, but I also don't want to back into something accidentally at 5 mph and my airbags go off. I backed into a gate a few months back going about 5 mph (just wasn't paying attention) but it makes me wonder if I had hit it more center instead of on the side of the truck if my airbags would have deployed.
 
You have to understand the rapidity of the acceleration / deceleration. Hitting a snowbank probably provides enough of a "buffer" that your deceleration wasn't nearly as steep a slope as getting hit while stopped or running into a relatively immovable object.

Also note that it's primarily only detecting front-to-back acceleration/deceleration. Getting hit sideways will not deploy your airbags.

My first 4Runner was totaled when it hit a tree (I was not the one driving it), but the airbags did not deploy even though the driver hit the windshield.

IMG_2212.jpg~original

Yeah, I hit a snowbank pretty much straight on going quite fast, started slipping at 50-55, airbags didn't go off.

The snowbank makes a huge difference in peak deceleration; lots of energy dissipation there.
 
when i say snatched by chains, i mean it. i got really, really, really, stuck after i first bought the 4runner 4 yrs ago and had to find someone to pull me out. i was pulled out in reverse (only option). dude was in a newer F150 4x4 and we had a longggggg chain (ONLY THING AVAIL). anyways, i thought my sht was about to get ripped in half. snatched was so intense ive wondered to this day what it really did to the ole 4runner. i mean, pulled so hard back tires came off ground over a small dirt mound. it was a dumb, dumb, DUMB thing for me to do, and cant say Ive done anything that stupid since. i guess short version of the point: airbags didnt go off, and im sure that i had a good deal of force goin on with that maneuver.

Good thing nothing happened, You don't want to end up like this guy...
YouTube - ‪Built Ford Tough!‬‏ Fun begins at 1:01
Full 6:22 clip
http://www.youtube.com/watch?v=HJA3J--g_yI
They ruined the video with music.
 
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If they only went off at a certain speed then if you were rear ended while sitting at a red light, your airbags wouldn't go off...
I don't need my airbags to deploy when struck from the rear. They do nothing in that case. Airbags provide protection to the body moving forwards, not backwards. When you are hit from behind the seat and headrest are pushed into your body.
I've been rear ended at high speed in my 4Runner and the airbags did not deploy because they are not designed to. Remember what SRS stands for, Supplemental Restraint System. They supplement the seat belt. The seat belt does not need additional help to restrain a bodies reaction force in a rear end collision because most of the energy is absorbed by the seat.
 
In retrospec this would have been good to know and would be saving me from having to repair the truck.

are you going to repair the truck?

Basically, is it really worth it? I was told that airbag replacement for whole set can be $2000+ and there is no shortcuts because of government laws. You may be better off just not reporting it, assuming you are keeping the truck for the long haul.

It is probably illegal to sell it with blown airbags - FYI.
 

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