There are several things to remember about airbags.
Any pulling of harnesses while the battery is still connected, they can trigger.
Large voltage swings can also trigger - affects calibration...
Poor ground and improper grounding can trigger...
Each one of the above - relies upon a "loop" there is a monitor inside the airbag module that sends out a calibrated trickle voltage to each live wire (usually Yellow or identified with Yellow as a stripe or line). A return wire goes back to the Module to a specific pin - this loop if broken will set a light on the dash and depending upon the severity - can set a more sensitive trigger method to compensate for the non-communicating one to at least protect the passengers even if not all airbags can deploy.
The Yellow wire can also emit an RF-ID pulse - which then makes the wire it's associated with, return an RF-ID "tag" due to the pulse, that the module processes as a means to set aspect of each "line" or loop - and what is attached to it - is.
The RF-ID tag strip is (if equipped) embedded in the Igniter assembly - the Igniter is a simple filament of thin wire between two electrodes - embedded in a mixture designed to amplify the heat and accelerates into a minor explosion (oxygenates) and since it's sealed in a close knit fabric, the rapidly expanding air fills the the volume of the bag - the expanding volume is enough to push into the container and itself having scored marks of thinner material can rip-break their seal and allow the bag to expand is a specific direction and speed.
- The RF ID, is similar to those found in Retail, the "BUZZ-BRAAP" you hear during the sale, that's the Tag getting pulsed to emit and defeat - burn out - the tag It's the one that emits when RF of a specific frequency pulse - the Tag returns a ping to it. Small little strip that sits in the igniter assembly and touches the electrodes - and RF pings it and there is also a small RF Ferrite "Bead" to help "tune" the response output so the DC voltage doesn't overpower the Ping
Once you know that process, you also have to be aware that many thieves and small car lot dealers will sell vehicles as used even though they've been sold for scrap - because the insurance company wrote off the vehicle because; even with the Airbag deployment - the cost of replacement is too costly for the price of the vehicle.
So they use several methods to get past the "Air bag Light" on the dash, including defeating mimicking the loop sense "voltage drop" as well as using after market Air Bags with untried or untested - non verifiable - ignitions an inflators even from the Takata Air Bag shrapnel days.
There lies the problem - older Modules use the "loop sense" while others use RF-ID's on top of the physical loop - to monitor and verify the proper airbag is installed in the right loop.
This process is why certain aftermarket resellers will offer to reprogram a faulty or deployed now error'd out (bad) Air Bag Module - they erase the old RF-ID and initiate new defeated codes to rely on the older Loop process. They return it all for a flat fee.
Sounds like highway robbery - and in some cases it is. I am aware of dealers that will try to fix something only to have more problems show up later - including the Air bag light - and say something to the effect that because of the malfunction - it caused you to have this new problem - which now raises your estimates $$$$ much...
Was it your or their error - if you don't know where you're air bag connectors are, then no - it's not your fault, the air bang wiring is a special loom in the harness - you'd have to be pretty abusive or darn smart to figure out how to make one of the connectors not work so it sets the light on the dash and all they have to do is resolder the wire back together.
Think this thru yet?
This is why RF ID is coming into play - and why RF in the vehicle can be a dangerous thing.
IF some jerk wanted to make your day, they can cut one of the loop wires to any Airbag - and you have your Dash light and some shops charge to have you review the their scanner data to find, diagnose reset and if possible locate the defective part(s) - quick Racket for that...
When you resolder some of these systems - the RF ID won't or cannot return back to the module - the wires' ability to return the signal is reduced - attenuated. The physical loop works - so you can clear a code for several drive cycles until the missing airbag ID-tag is showing "not there" and you'll get your light back on the dash.
The problem is with the integrity of the system, not necessarily the RF - the RF ID is one aspect, but a faulty or open sensor can also trigger events because your RF signal from the amp has swamped out the sensor and the module is seeing input that looks like a strike - causing deployment - or worse, NO deployment because the systems' integrity is compromised to a point that the module malfunctions.
Just so you know, if you've ever messed with "ESTES" rocketry kits, you have used igniters that are similar in construction and power just like the Airbags use - similar in both - low-battery voltage presence and boom - off she goes into the sky...So when in Rome...or in your car, you're not very far, from getting Vexed by the Man who Wears the $tar - to Fix your car.
I'm with
@Slowmover on this, too many open leads and Mickey "D's" French fries, ketchup and Salty packets - It's a self immolating mess in between the seats...
