Question about SRS airbags

Post by **Volvofan94** » 04 Dec 2012, 12:02

Hi Everyone,

Thank you for everyone's help while I work on my Volvo. This site has been a valuable resource for me to look up information when working on my car. Keep up the good work!

I do have a question, this time on the SRS airbag system. If this has been answered before, please direct me to the correct post. After a collision, where the driver and passenger airbags deployed, are the main airbag components safe to reuse? I'm referring to the SRS computer, seatbelt tensioners, crash sensors, or does it take only one collision they need to be replaced? I've done some searching and read some success stories from other 850 owners, but I'm wondering if any of these components in the car work fine after a collision.

Thank you for your assistance!

Post by **vjaneczko** » 04 Dec 2012, 13:03

I'd go in with the thought that everything is shot and be happily surprised if anything is good. When the airbags are deployed, odds are pretty good that the belt tensioners were deployed as well. Not sure what the bags would cost to replace, but at “our ages”, I’m guessing more than the cost of buying an identical car that works.

I don’t think the sensors are damaged when the system deploys the bags, but they may have been damaged by the impact.

The SRS computer would be in a fault state which can only be reset by a dealer – which for me cost 85 bucks to have the light reset when I accidently connected the battery when the passenger airbag was disconnected.

Post by **Ozark Lee** » 04 Dec 2012, 13:48

The way the SRS works, with the exception of SIPS bags, is that if one blows, they all blow including the seat belt tensioners. The SIPS bags are controlled by a separate trigger that is mounted on the seat frame.

Replace everything, you can do it with junk yard parts so long as the air bags have not deployed on the donor car. Obviously, avoid flooded cars since it will cause connector problems.

...Lee

skloon · Post by **skloon** » 04 Dec 2012, 13:55

You may be able to reuse the computer as the 94 can be reset under the hood the rest has to be replaced though

Post by **Ben850** » 04 Dec 2012, 19:13

Your '94 will have the same SRS module as my '93. I found one in a '95 at the yard. These three years had the same ECM located under the console.
The seat belts, drivers airbag, and passengers dashpad airbag will all have been activated within measured milliseconds by the impact. The steering wheel clockspring may have also broken from the deployment. So all these will need to be replaced.
I did go through this if you would like to look at this thread.

https://www.matthewsvolvosite.com/forums ... =1&t=45262

Good luck.

Post by **Volvofan94** » 04 Dec 2012, 22:57

Nice work Ben850! Really like what you did to your Volvo. Did you have any surprises hooking up your new airbags?

I'm working on rebuilding the whole dashboard on my Volvo after the airbags deployed earlier. Thankfully the body and frame weren't damaged badly so I could focus on cleaning up the interior. The dashboard needed to be replaced; many plastic parts everywhere! Found a 850 from the junk yard with the same color interior as mine and pulled out everything I would need to get it done. I also grabbed some airbag parts as well. I still need to grab the SRS computer and seatbelt tensioners, but I can pick those up this weekend.

Here's what I have so far for the car:
1. Driver and passenger airbags
2. Clockspring (replaced and installed)

I need to get the seatbelt tensioners and SRS computer from the junkyard. Is it pretty straightforward to remove and install the seatbelt tensioners?

Post by **Ozark Lee** » 05 Dec 2012, 09:39

Volvofan94 wrote:Is it pretty straightforward to remove and install the seatbelt tensioners?

It is a piece of cake. Two bolts hold the assembly to the B pillar and then there is one torx screw that holds the SRS retractor. On the bottom side there is one bolt that holds the bottom of the belt in place on the seat frame. The B pillar trim just pops off - I wouldn't mess with it much below 50 degrees as the plastic gets brittle and can crack.

I don't have any pictures of the top but here is the anchorage on the seat frame.

: DSC01968.JPG (213.43 KiB) Viewed 4503 times

...Lee

Post by **Volvofan94** » 09 Dec 2012, 09:51

Went to my local junk yard yesterday and found a 93 850 GLT with both driver and passenger seatbelt tensioners and the SRS computer. All parts looked to be in good working condition. I completed removing and installing the new dashboard and am getting ready to remove the deployed airbag parts (from my car) and replace with the parts on the 93.

I've read somewhere before you reconnect the battery, on some Volvos, the key needs to be in Position II for the SRS light not to illuminate? Is there a procedure to properly reactivate the SRS system with minimal risk of the airbag accidentally deploying when power is first connected?

Post by **jimmy57** » 09 Dec 2012, 10:13

The key is turned on before batt is connected as a safeguard. If something is wrong you will be by battery and not in the reach of any deploying airbag. Lamp gets lit if you power up and anything is unplugged.

Crash sensor/airbag module only needs to be replaced if it will not clear codes. Rarely does the sensor not clear, usually a severe wreck where the internal sensor gets damaged which is usually a car that will not be repaired.

Post by **Ben850** » 09 Dec 2012, 10:44

The SRS light may be recalled by the cluster from the accident, but you can reset it through your OBD I on the B5 port.