Airbag replacement

Tiny
DKB92
  • MEMBER
  • 1997 MERCURY SABLE
  • 120,000 MILES
My cars air bag system went off. Are airbags expensive to put back in?
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Monday, September 26th, 2011 AT 8:11 PM

4 Replies

Tiny
CARADIODOC
  • EXPERT
How about some information? Did someone remove them to perform other service, and now you're left reinstalling them? Did they pop in a crash so you need new ones? Is the air bag warning light on, but the bags never deployed? Just the driver's side bag or passenger side too?
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Monday, September 26th, 2011 AT 8:31 PM
Tiny
CALEB CORBETT
  • MEMBER
I have the same issue. Hit a deer at 55 mph two nights ago. Airbags went off on both sides. What do I need to replace to fix the airbag system? Car faced little to no damage other then the windshield and hood. Anyone can help?
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Wednesday, June 24th, 2020 AT 1:43 PM
Tiny
CALEB CORBETT
  • MEMBER
1997 mecury sable.
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Wednesday, June 24th, 2020 AT 1:43 PM
Tiny
CARADIODOC
  • EXPERT
You really should start a new question specific to your vehicle. Unlike other sites where anyone can chime in to confuse the issue. this becomes a private conversation between just the two people involved. As such, none of the other experts will see your addition or have a chance to reply. That may not get you the help you need. I'll try to get you started, but if necessary, you can start a new question here:

https://www.2carpros.com/questions/new

The first four drawings are for replacing the two air bags, but there is usually a lot more involved with this repair. In 99 percent of air bag deployments, the electrical connector is melted from the heat of the burning rocket fuel. Half of that connector is on the "clock spring" under the steering wheel.

Be aware that less than 12 volts is needed to fire an air bag. When you're holding it in your hand, it is susceptible to static discharge. When you walk across a carpeted floor, then get a shock when you touch a door knob, that is at least 3,000 volts, so it's easy to see why there are so many safety warnings related to air bags.

All air bag system components in the "squib", or initiator circuit have shorting bars that short the two wires together when that component is unplugged. Once that is done, regardless of how much static electricity is presented, both wires will see the same voltage. The difference will be 0 volts, so the bag will not fire. The concern here is with the shorting bars in your replacement air bags. Since the mating connector on the clock spring is almost certainly melted and deformed, while you might be able to force it to plug in, it is likely going to bend / damage the air bag's shorting bar. That could present a danger the next time the air bag has to be removed, or it could keep the two circuits shorted together once plugged in. You'd see the "Air Bag" warning light stay on, and the new air bag would not deploy in a crash. This is why we always replace the clock spring. The fifth drawing shows that.

Clock springs have a well-known history of failure from the internal ribbon cable coming apart on one end. For that reason, avoid a used assembly from a salvage yard. Used air bags are okay, but spring for a new clock spring from the dealer. Be aware too they can only rotate slightly more than the steering wheel will turn from full-left to full-right. All new clock springs come locked in their centered position. It is required to have the car's steering system perfectly centered when the clock spring is installed. If the steering system is off by just one revolution, when you turn fully one way, the ribbon cable is going to wind up tight, then tear off on one end, or it is going to unwind too far, then fold over on itself. If the cable winds up too tight and tears off, the "Air Bag" warning light will turn on right away, and the computer will shut the system down. If the cable unwinds too far, it will fold over on itself multiple times before it snaps. That could take weeks or months to show up. The computer will set a diagnostic fault code related to "Open Squib or Initiator".

Next come the sensors. Impact sensors use a weight on the end of a coiled-up piece of spring metal. When that unrolls in a crash, the weight touches a pair of contacts that sends a signal to the computer. The current can cause arcing on those contacts. The fear is those arced spots are likely to be exactly where the contacts will land the next time the sensor trips, and it will fail to signal the computer resulting in no deployment when it is needed. For liability reasons, no conscientious mechanic will fail to replace the sensors as part of a proper repair.

The same thing for the "safing" sensor. That one sits inside the Air Bag Computer. This sensor, along with at least one impact sensor, must trip at exactly the same time for the air bags to deploy. I included the directions for replacing the sensors.
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Wednesday, June 24th, 2020 AT 7:29 PM

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