So, I've been chasing this gremlin for nearly 3 years, and I think I might have him cornered? Every so often the airbag light and chime would constantly come and go. I noticed this happened more often in humid conditions. The light would come on, then the guages would quit. Truck would run just fine. Datalink gave me temp and spedo in a snap. Sometimes the CEL would throw a code for the output shaft speed sensor. I changed it and no issue for nearly a year. We'll, I took it on a road trip, and the light came on and the guages all quit. I tried a new clockspring. No change. Today I removed the module and the guages came back to life! Going to a local wrecker tomorrow to try another module.
i think there might have been a water issue. The prior owner had a sound system installed, and the installer broke the duct, and condensation was dripping in the floor. I have my suspicions that that triggered this. I'll follow up after I try the module test.

 

Replacement airbag controller fixed the issue.....now the parking brake won't turn off...jeez