I had the same problem recently with my 03. The “Service Air Bag” message started appearing intermittently in the DIC then the control buttons on the steering wheel became intermittent. Eventually the Service Air Bag Message would stay on and all the buttons stopped working …Turned out to be a bad SIR Coil (clock-spring) which is under the steering wheel. The SIR Coil is a spiral wound flex-tape circuit housed I in a circular plastic case. It provides the wiring connection between the moving steering wheel and the stationary wiring harness on the steering column. The SIR system is complex with multiple sensors (motion/position/seat) and an SDM - Sensing Diagnostic Module. The SDM periodically measures the Air Bag circuit resistance and if it finds a fault, the air bag light and message turns on. When first looking for the problem I pulled the SIR fuse to disable the system – wait at least a minute for the system to discharge before working on it. Next I removed the knee bolsters and checked all the SIR (Sudden Impact Restraint) system wiring (yellow wires and connectors) including connections to the SDM under the driver’s seat … didn’t find anything that was loose and/or damaged. Given the steering wheel buttons had also stopped working it pointed to the SIR coil. I installed a new SIR Coil (cost $214 – $300 list ) and it’s fixed. couldn't just buy the coil – its part of the steering wheel wiring harness so the whole harness has to be replaced.... knee bolsters, dash covers, airbag, and steering wheel have to be removed ... GM steering wheel puller is also needed.
Bill
03 2500HD D/A CC/SB/4WD,OilGuard, MegaFilter,LiftPump/PreFilter, Bilsteins,RetraxRollTop,J&J Boards,Coolant Filter,AlliDeepPan,FastIdle,AllHeadLightsOn,
98 K3500 6.5,SOLD