I'll explain something to you, if it helps out with getting GM to pay the claim, so be it.
First, let's rule out the front discriminating sensors they have NOTHING to do with the deployment of side air curtains. The sensor(s) in the front are discriminating sensors, they are used to signal the SDM (sensing and diagnostic module) if a stage 2 deployment of the FRONT air bags is necessary. These sensors CANNOT signal an air bag deployment; only thing that can signal and actual deployment of the front air bags is the SDM! So DON'T mention that to GM.
Now, onto the side air curtains. There are two ways they can deploy as programmed. One is the side air bag sensor, located in the B-pillar is crushed in an accident. This would be easy to note, since the B-pillar would have some massive damage to it. This is the side curtain deployment.
Second way is a triggered rollover of the vehicle. The rollover sensor will signal a possible rollover, SDM will make a determination from the signal as to if it needs to deploy the side bags. During a signaled rollover event, both side curtains will deploy and unlike standard side air curtains, with a rollover type system, the bags will remain deployed for a longer period of time. (Another discussion for another time.)
There are a few ways this system can fire off the side air curtains due other reasons.
One, the rollover sensor is defective and noted a possible rollover. This does happen at times when offroading. It should not happen, but GM likes to blame you so your insurance company will pay. My opinion has always been tough **** GM, this vehicle is designed to go off road and it should not deploy a side curtain unless you are actually over 45 degrees from upright. Another way is if someone screws around with the wiring and deploys a bag. That's usually quite apparent since it happens while you are playing around with the wrong circuits ii the wiring harnesses. And usually only the bag you tap into will deploy since they are all on separate circuits.
GM should pay for the simple reason there is NO damage, and no one tapped into any wiring. As for mud; damn you can get mud on a major interstate if it rains hard enough. As far as the code...well anytime air bags or air curtains are deployed by the SDM there are CODES set in the SDM (and transferred to the BCM). Other than if you connect a hot to a deployment wire when messing with the wiring, there is a code. In fact, air bag deployment codes (most, not all) cannot be wiped from the computer, a new SDM must be installed.
So, my humble opinion is, and always has been, if there is NOT visible damage to the side B-pillar, or there is no evidence of a rollover, GM is responsible and need to pay for the repair. Anything other than that, is a crock of BS; which GM is great at slinging around.
