Why would this wire be shielded?
First note that you are messing with systems directly related to the control of your vehicle's airbags - a safety critical system that can really hurt you or kill you:


If you need it to work and it doesn't, and 
If you expect it to not work and it does


Work on this system at your own risk.

The Weight Sensor Control Module provides amplification and filtering for individual seat sensors.  It interfaces to the airbag control module using a proprietary protocol that you will need to reverse engineer with a scope and/or protocol analyzer  (sorry - automotive electronics is tough if you don't have support from an OEM (Original Equipment Manufacturer) or supplier.  

A typical arrangement looks like this 
(your sub-circuit in green box -- note that in for the vehicle shown, the line is not shielded).