JeepForum.com - Reply to Topic
Thread: Replacing Airbags...Hard? Reply to Thread
Title:
Message:

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in










  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
05-22-2015 07:12 PM
EricsGreen98Tj So to bring this back up, OP what did you find out?

My 98 has had a blown drivers airbag for 3 yrs now. I finally got around to ordering a replacement along with a clockspring.

Do I need to do anything to the ACM (airbag control module)? Except unhook the battery for 5 or so minutes..


I replaced both airbags and clockspring in my MIL's 04 Tj and didn't do anything to the ACM. Are the early Tjs the same?
12-11-2010 10:52 PM
mrblaine
Quote:
Originally Posted by lostone73 View Post
You say tomato I say TOMATO, I tend to err on the "overdoing it" side do to the HUGE liability involved with collision repair. Since I am employed by a multibrand shop, we cannot possibly have every FSM on the shelf. We do however subscribe to a very expensive computer database that reccomend what to replace after a deployment that is vehicle specific. The Insurance companys use it as well.
No, you don't have every FSM on the shelf, but since we happen to be in a TJ specific area, I don't really care how many other brands you work on, with, or around. If you want to err on the side of caution, that's your business. If you wish to tell some Toyota or Honda owner something about their vehicle, same again, knock yourself out.

So, in that vein, please consult your very expensive data base and get back to us. I'd be interested in seeing if it contradicts the FSM.

Quote:
My wheeling buddys dont like the way I do things either, I wont help replace a waterpump without a new t-stat, new hoses, and a complete flush and inspection. Nor will I only replace a noisy T/O bearing, it gets a disk,bearing, pressure plate and possibly a new flywheel and possibly a rear main seal.

I think we are picking fly **** out of black pepper here and wasting bandwidth, Ill close with this again. G'nite
I think if you look around we have similarities. I tend to err on the side of accuracy. Anyone can take a shotgun approach and replace everything.
12-11-2010 09:29 PM
KKiowaTJ Yes, Even with the battery disconnected it can deploy. Static electricity will detonate one. I popped a couple with a 9 volt RC car remote battery and they will kill you with a direct blow to the head.

The module you are referring to is a BCM, Body control module. It stores airbag deployment etc. But it is still good unless sitting in water, Tub fire or you have taken it apart. Its not like the old gold pendulum thats good once.

Also pay attention to the new clock spring when assembling, So you dont go and turn the wheel too far and it deploys. Good luck
12-11-2010 09:28 PM
lostone73 You say tomato I say TOMATO, I tend to err on the "overdoing it" side do to the HUGE liability involved with collision repair. Since I am employed by a multibrand shop, we cannot possibly have every FSM on the shelf. We do however subscribe to a very expensive computer database that reccomend what to replace after a deployment that is vehicle specific. The Insurance companys use it as well.

My wheeling buddys dont like the way I do things either, I wont help replace a waterpump without a new t-stat, new hoses, and a complete flush and inspection. Nor will I only replace a noisy T/O bearing, it gets a disk,bearing, pressure plate and possibly a new flywheel and possibly a rear main seal.

I think we are picking fly **** out of black pepper here and wasting bandwidth, Ill close with this again. G'nite













Quote:
Originally Posted by lostone73 View Post
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.
12-11-2010 09:06 PM
cosmo_j this is alittle off the thread topic but if i were to remove the airbag fuse would the airbags still be able to deploy???
12-11-2010 08:53 PM
mrblaine
Quote:
Originally Posted by lostone73 View Post
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.
12-11-2010 08:11 PM
lostone73 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
12-11-2010 08:02 PM
lostone73 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.
12-11-2010 08:00 PM
mrblaine
Quote:
Originally Posted by lostone73 View Post
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.
12-11-2010 07:54 PM
mrblaine
Quote:
Originally Posted by lostone73 View Post
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.
12-11-2010 07:42 PM
lostone73 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
12-11-2010 07:29 PM
Jerry Bransford 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.
12-11-2010 07:24 PM
lostone73
Quote:
Originally Posted by Jerry Bransford View Post
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.
12-11-2010 07:16 PM
flatlander757 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.
12-11-2010 07:02 PM
Jerry Bransford You don't need a computer module, you just need replacement air bags.
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

 
For the best viewing experience please update your browser to Google Chrome