GMC Repair: Service Airbag message, gmc sierra, sir system

Question
I have a 2003 GMC Sierra 1500HD, Vortec 6000 V8, 4x2.  The service airbag message appeared yesterday.  How many sensors are there?  I am guessing 4.  One under each front seat and one on each side of the front bumper?  any help appreciated.

Answer
Hi
The SIR system uses many different inputs to determine a fault. It could be anything from a terminal inside a connector to a failed module.
I would highly suggest taking it and having the trouble codes read. That way the fault could be pinpointed and save the un-necessary replacement of parts, that may not resolve problem.