Changed third brake light to LED and the "Service Airbag" light came on control panel?

third brake light problem ' Chevy Silverado and GMC Sierra Forum (silveradosierra.com)
Separate fuse for 3rd brake lite check link above.

It sounds like the LED controller built into the center stop light is malfunctioning. The only suggestion I have is to replace the light strip.

Year/make/model didn't post. The high mount brake light is not fused seperately. It should be on the same fuse as the brake lights. If it is not working check for a bad bulb. If the assembly is LED, check for power and ground at connector to light. If power and ground ok, suspect defective LED assembly

You need to take the back seat out. Remove the C-Pillar trim panels. Lift up on the package shelf. Unplug the wiring connector. I've had mine out when I changed the speakers.

BTW, Its Not a Bulb. Its a LED Assembly. Replaced as a whole unit. Unless your good with electronics and soldering.

bad english accepted i come from the east end of london originally where english is the third language ,so what iam reading here is you have a problem with horn and the lights ,Now on this model if my memory serves me correct the brake lights will come on with the handbrake on ,but if its a auto version then the brake lights could be affected cruise control and what i think without a look myself is that the wires on the bottom of the steering wheel for the cruise and the radio horn ect run through the steering column and somehow they are damaged or twisted up and the only way is to remove the steering wheel to have a look ,to do this you must disconnect the battery first because if the airbag goes off accidently and your head is in the way then your dead .To get the stering wheel off you will have to remove the airbag unit first ,think its two torq 20 screws but it could be a 7mm headed nut ,remove the airbag then unplug it and then you can undo the big nut in the middle ,cannot remember the size of the nut though but once its off then the steering wheel comes off but its on a splined shaft so it may need a puller to get it off but i often use a piece of wood under a spoke and hit it with a 2kg hammer ,doesnt always work first time but normaly it does then you will tracks for the different controls .

Check the brake light switch that is close to the brake pedal it may be out of adjustment

If the third brake light always works, then it is the turn signal switch. If the third brake light does not work, it is probably something else. The turn signal switch is in the steering column. You have to remove the airbag and steering wheel, take out all of the componets and replace the turn signal switch. Special tools are required and a moderate level of mechanical ability. Watch the airbag, it can go off and cause serious injury!!

HI, there isn't a fuse that can cause your 3rd gear failure and since driving it like this will only cause more damage to the transmission, and the Airbag light is telling you the system is not working. I strongly recommend you take to your service center. Glad your ABS did its job.

It should plugin within the door. You will have to remove the door panel to access the plugin.

The third break lights are LED and the circuit board may have gone bad or the solder may have gone bad. The circuit board is built in the third brake light and is a seal unit. You may have to replace the unit, there is a relay for the third brake light and that is located on the glove box behind the panel that say's relays. There are three relays in there, the center is for the fuel pump and the two out side are for the A/C and third brake light. Just swap them around and see if the brake lights come on. Good luck and keep me posted.