There may be several reasons it's coming on but here are a few common problems that GM has addresses. Check them out and it may be necessary to have the trouble codes scanned so you know what exactly approach to take and diagnose.
#03-05-25-005: Service Stability Message and DTCs C0455 or C0550 Set (Update Vehicle Stability Enhancement System (VSES) Module Software) - (Aug 20, 2003)
Some customers may comment on one or more of the following concerns:
Technicians may find Diagnostic Trouble Code (DTC) C0455 and/or C0550 set.
Technicians are to update the VSES module with new software. The new software will be available in TIS version 6.5, scheduled for release on June 15, 2003. All 2004 model year trucks built prior to June 16, 2003 will also need the VSES module software update.