Thanks for using Just Answer, if you are replacing the switch you will not have to depower the SRS, I am sending you instructions on how to test in pdf format, in order to properly diagnose you will need a DVOM (Digital Volt Ohm Meter), which can be purchased at your local auto parts store, for around $50.00 or less. Hope this helps you out.
CLICK HERE FOR TEST PROCEDURES
CLICK HERE FOR SWITCH REPLACEMENT
No problem here you go,
CLICK HERE FOR INSTRUCTIONS
THANKS AND SAME TO YOU!