Replace the tail light assembly. You can try to reseal it if you can find where it's leaking but I've tried and had little success in the long term. The other thing you can try (if it's filling up with water) is to drill a small drain hole or two in the bottom and let it drain instead of filling up.
With a scan tool.
The same as you do in the 1968 Buick Wildcat
The diagnostic code 410, on your 2004 Chevrolet trailblazer, is a reference to a vacuum hose problem. Check the vacuum hoses to make sure they are all connected.
In a 2003 Chevrolet Trailblazer, the reverse light wire can typically be found under the driver's side dash near the steering column. You may need to remove a panel or cover to gain access to the wiring harness. The reverse light wire is usually part of the vehicle's wiring harness and may be colored light green with a black stripe. Always refer to a wiring diagram specific to your model for confirmation before making any connections.
On a 2003 Chevrolet TrailBlazer, the brake light switch is typically located above the brake pedal, mounted on the brake pedal assembly. To access it, you may need to remove the lower dashboard cover or panel. The switch is usually a small component that activates the brake lights when the pedal is pressed.
how do you remove dome light lens on 2008 trailblazer
How do I reset the service engine light on a 2003 Chevy Trailblazer?
You must remove the plastic panels that cover the back of the taillight from the inside of the truck. Check for the scews behind the caps then pull the rest of it off.
A few weekends ago I had to replace the fan clutch on my '06 Trailblazer EXT LS. In addition to getting the P0495 code from the check engine light, when I rev'd it up it sounded like a jet engine. Instructions: http://www.diystew.com/2006-trailblazer/
how do you replace side marker light on 2008 chevy trailblazer
can you tell me why my 1999-2000 Chevy trailblazer light is on
You must first get the code read and find out what made it come on. Then the code can be errased at the same time with the code reader. If the code was an anomalie then the light will go out after 3 or 4 drive cycles.