Headlights on 2005 chevy avalanche went out and all fuses and light bulbs are ok. what do i do do i check the relays and which one are they?

SOURCE: Chevy Avalanche won't start

If you're getting no power at all when you turn the key to start, try disconnecting the battery and then hook it back up. Chevy has had some problems with an ignition relay solenoid that's mounted under the driver's side dash. Disconnecting power could reset the switch....If that seems to be it, a replacement is around $250. at a chevy dlrshp.

SOURCE: Tail lights don't work on 1998 Chevy Silverado.

check the wiring from the tailights back to the fuse panel, it sounds like an open connection. if i recall correctly check under the dash on the drivers side near the fuse panel for a bunch of wires in a bundle and look carefully for a wire or two that are cut/shorted/or seperated, you can also check under the drivers side kick panel by the hood release.

SOURCE: 2004 chevy impala no headlights

there's a button on the right side of the steering wheel that says serv push that button. It's put right there for when they use them as police cars you can cut the headlights off. You will probably notice that dash lights are on.

SOURCE: chevy cavalier 1996 headlight not working,day

Did you replace the relay for the day time running lights which for some dumb reason is mounted under the front bumper? Climb under and look straight up and you should see it...mine was mounted in about the center (on the frame in front of the radiator. Sounds similar to an issue I had and it cleared up once I replaced the part...had to get from dealer still.

SOURCE: 2002 Chevy Avalanche. Truck will not

Do a bench test on the starter. Remove starter, hook up a ground cable to starter, and positive to two prongs on starter and it should spin. You can do this in vechile too but not suggested due to risk of injury. If it doesn't spin, probally a solenoid or the starter it self. Unlikely but possible.