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-   -   Replacing Airbags...Hard? (https://www.jeepforum.com/forum/f9/replacing-airbags-hard-1139812/)

ipodblue12 12-11-2010 04:47 PM

Replacing Airbags...Hard?
 
Well, i got in a wreck in my 2000 Jeep Wrangler Sahara and both driver and passenger airbags deployed. How hard is it to replace them and what all do i need? Also, do i have to get them inspected by someone after?
Thanks

flatlander757 12-11-2010 05:13 PM

It's easy... basically you just remove the bag from the steering wheel and reinstall the new one.

Do it with the battery disconnected for safety reasons. You'll need the airbag module.

While I'm sure you could find one "used", I'm fairly certain it is illegal to reuse airbag parts... so check into that... may need to buy new from the dealer.

edit: Not sure about the passenger side airbag... it is usually a little more involved on most vehicles(remove glovebox and either contort around stuff to remove the airbag pad or remove the dash almost entirely). I haven't had one out of a TJ myself... but have on many other Chrysler vehicles.

Jerry Bransford 12-11-2010 05:20 PM

The passenger side is a PITA since it involves removing the dash which is why I haven't installed my replacement airbag yet.

ipodblue12 12-11-2010 05:49 PM

So all i need is one computer module? or one for each airbag?

Jerry Bransford 12-11-2010 06:02 PM

You don't need a computer module, you just need replacement air bags.

flatlander757 12-11-2010 06:16 PM

It is the physical steering wheel "pad" that has the airbag assembly as a part of it.

Same with the dash pad... it will be the airbag assembly including the pad that you see on the dash.

lostone73 12-11-2010 06:24 PM

Quote:

Originally Posted by Jerry Bransford (Post 10603891)
You don't need a computer module, you just need replacement air bags.

You must replace the airbag computer, once it stores a deployment command it cannot be cleared. Its done, finished, Kaput. Of course you can replace just the Airbag modules themselves for appearance reasons. They just wont work again until you correctly replace the SDM(computer).

SDM (sensing and diagnostic module) is inside the passenger compartment just ahead of the gear shifter. The SDM also contains the Discriminatory Sensor.

Replace Dashs and Airbags daily at a Large Multi-Brand collision center. The Jeep Wrangler is not too tough for either side. Take your time and reassemble everything the EXACT way it was originally, the integrity of the system depends on it.

FWIW Acura and Honda are the absolute worst to repair from an airbag perspective.

Jerry Bransford 12-11-2010 06:29 PM

Could you actually be talking about the airbag control module (essentially an impact sensor) which is really just an impact-activated switch mounted under the console at its forward-most position? I know about the airbag control module sensor, I have never heard of an airbag computer in the TJ.

lostone73 12-11-2010 06:42 PM

Depends on the year model, in my 2000 the box in front of the shifter contains the forward crash sensor AS WELL as the Diagnostic computer.

I dont know how it is configured in your 2004, it may be two separate units. I do know that it logs the data of the crash( veh speed, brake pedal status , rate of decelleration, ABS status, seatbelt use , ect). That has been required on all us vehicles since 1996 or 1997 per the DOT and NTSB.

In my experience, all 2nd generation airbag crash sensors, once tripped (command deployment), stay that way just the way they were made. They are basically a steel ball held in place by a calibrated magnet, when enough force comes along to dislodge the ball, it contacts two sharp pins and completes a circuit. The frontal impact sensor and the Discriminatory sensor must accomplish this task within .50 Ms (not sure of the exact spec).

Jerry, by all means, give it a try. Maybe the collision that deployed your TJ bags wasnt enough to really waste the whole computer. Damn sure not going to hurt anything to try. Just use common service precautions( battery disconnect, ECT).

My .02

mrblaine 12-11-2010 06:54 PM

Quote:

Originally Posted by lostone73 (Post 10603989)
You must replace the airbag computer, once it stores a deployment command it cannot be cleared. Its done, finished, Kaput. Of course you can replace just the Airbag modules themselves for appearance reasons. They just wont work again until you correctly replace the SDM(computer).

That is not correct according to at least the 2001 Jeep Wrangler FSM. It says to only replace the ACM if it has suffered external damage.

mrblaine 12-11-2010 07:00 PM

Quote:

Originally Posted by lostone73 (Post 10604082)
In my experience, all 2nd generation airbag crash sensors, once tripped (command deployment), stay that way just the way they were made. They are basically a steel ball held in place by a calibrated magnet, when enough force comes along to dislodge the ball, it contacts two sharp pins and completes a circuit. The frontal impact sensor and the Discriminatory sensor must accomplish this task within .50 Ms (not sure of the exact spec).

Jeep TJ's use an accelerometer and a microprocessor to fire the bags or verbatim from the FSM- When a frontal impact is severe enough, the microprocessor in the ACM signals the inflator units of both airbags to deploy the airbags.

lostone73 12-11-2010 07:02 PM

At this point its a matter of opinion, nevertheless, crash data is stored in that ACM....Period. I Get paid to put the vehicle back to pre accident condition, which doesent include a crash event stored in the ACM.

Its all falls on ethics I guess, If Jerry wants to see if it will work without a new computer, I encourage it. It cant hurt a thing.

Back on topic to the OP question, Yes you can replace airbags in your TJ. If you are capable to replace a heater core, you can relace your airbags.

lostone73 12-11-2010 07:11 PM

In addition to the electronic impact sensor, there is
an electromechanical sensor within the ACM called a
safing sensor. The safing sensor is a normally open
series switch located in the airbag deployment circuit
of the ACM. This sensor detects impact energy of a
lesser magnitude than the electronic impact sensor,
and must be closed in order for the airbags to deploy.
The ACM also contains an energy-storage capacitor.
This capacitor stores enough electrical energy to
deploy the airbags for up to one second following a
battery disconnect or failure during an impact. The
purpose of the capacitor is to provide airbag system
protection in a severe secondary impact, if the initial
impact has damaged or disconnected the battery, but
was not severe enough to deploy the airbags.

This is the steel ball MECHANICAL SENSOR I was refering too.(I called it the discriminatory sensor, as called by I-CAR)

Page 8M-4 2000 FSM

mrblaine 12-11-2010 07:53 PM

Quote:

Originally Posted by lostone73 (Post 10604221)
In addition to the electronic impact sensor, there is
an electromechanical sensor within the ACM called a
safing sensor. The safing sensor is a normally open
series switch located in the airbag deployment circuit
of the ACM. This sensor detects impact energy of a
lesser magnitude than the electronic impact sensor,
and must be closed in order for the airbags to deploy.
The ACM also contains an energy-storage capacitor.
This capacitor stores enough electrical energy to
deploy the airbags for up to one second following a
battery disconnect or failure during an impact. The
purpose of the capacitor is to provide airbag system
protection in a severe secondary impact, if the initial
impact has damaged or disconnected the battery, but
was not severe enough to deploy the airbags.

This is the steel ball MECHANICAL SENSOR I was refering too.(I called it the discriminatory sensor, as called by I-CAR)

Page 8M-4 2000 FSM

Mine says similar, but one would readily surmise from the section stating which components SHALL be replaced because they are not intended for REUSE, that it is odd that the ACM is specifically NOT mentioned, when the airbags, Driver airbag trim cover, horn switch, the clockspring, and passenger airbag door are.

It's your job to do as you see fit, I only checked the FSM out of curiosity and found nothing about replacing the ACM and the description of the switch would seem to indicate that's it's not a single use ball trapping mechanism you made it out to be.

cosmo_j 12-11-2010 08:06 PM

this is alittle off the thread topic but if i were to remove the airbag fuse would the airbags still be able to deploy???


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