no brake, reverse lights or blinkers

[b_barlan]

My 98 Sierra has no brake or reverse lights, nor does it have rear blinkers. Its not a fuse or bulbs, and they quit working at different times. Any suggestions? Im gonna try the brake light switch

[pies]

had the same problem with an 03, look at the back of the truck between the frame rails and see if there is a module, check the plugs on the module, the 03 one plug was loose. if no module, and all lights don't work, then trace wiring, you have a ground problem some where.

[gilbert2121]

Also try tightening the check valve on the brake booster.
I have NOOO idea why but that solved the same problem on my 89.