Most likely a broken wire in the hinge area of the door.
Here's how to remove the trim panel
http://www.ricksfreeautorepairadvice.com/uncategorized/remove-a-door-trim-panel-from-any-vehicle%E2%80%94-without-a-diagram
Here's how to test the window motor
http://www.ricksfreeautorepairadvice.com/repair-topics/window-power-repair/replace-a-power-window-regulator
my 02 Chevy trailblazer rear wiper is not working
If your Chevy trailblazer 2004 gauges are not working, check your fuel pump.
the air pump on 2005 trailblazer is located on the frame rail on the drivers side .by the drivers door
Drivers side on front of engine compartment
Drivers side at the top of transmission
under the back seat.. drivers side
take to dealer. doors have a control module in them either needs reprogram or replacement CHECK YOUR FUSES.
Drivers side frame between the doors.
See answer for same question on 2004 Chevy avalanche. JIT
First check the fuses.
The sensor is located in the front of the vehicle. On my trailblazer it is just behind the grill on the drivers side. You can't miss it.
The 2003 Trailblazer (GMT360 platform) uses a PCM and it is located on the drivers side of the engine. It has three connections bolted to it.