here's a few ideas...
the sensors are located in the b-pillars. There are 4 total. 2 are forward facing, and 2 are rearward facing. They are at the very top of the b-pillar.
Taking down the b-pillar plastic should be treated the same way as letting a dentist rummage around in your mouth. It is a slight puzzle as to how to get those plastic pieces off without breakage, so in other words be very careful.
Basically, you can temporarily move the sensors (within the plastic covers) from side to side in the car. This will tell you if it is the sensor, or the wiring.
An "open circuit" isn't necessarily a wiring issue. It could be that the smoke was let out of the sensor, and the module is calling, but no one is home!