Service airbag light is on

That means the computer detected a problem, set a diagnostic fault code so the mechanic will know where to start the diagnosis, turned the system off, and turned the warning light on to tell you. Your mechanic will provide the repair estimate based on his diagnosis. Common causes can be a wheel speed sensor, a broken "clock spring", (that is a wound-up ribbon cable under the steering wheel), and on GM trucks, rust under a front wheel speed sensor and shorted pump motors.

You can drive the truck, but the air bag will not deploy if you are in a crash. That can become a factor to the insurance company if you are driving a vehicle with a known inoperative safety system.

The first step is having the fault code read and recorded. Most independent repair shops should be able to do that for you.

Here is a video that shows how to get the codes so you can fix the problem. Probably the clock spring behind the steering wheel.

https://youtu.be/gnSGfEqrf_w

Please run down this guide and report back.

Cheers, Ken