How do you change tail lights for the 2003 passat

The dash lights are on a different fuse and circuit from the tail lights.
If the lights in the instrument cluster work, the problem may be in the harness in the dash.

On the 2001 Volkswagen Passat, there is one reverse tail light (bulb) per side for a total of two reverse tail lights. The following link shows the inside of the 2001 Volkswagen Passat tail light.
Link to 2001 Volkswagen Passat Image

You may have to replace the whole tail light because the a circuit might be shorted in the tail light.

open trunk and pull back carpet around light. Remove 2 nuts, then the tail light needs to be pulled out because it is held in by a clip that can be snug at times. Once out you have access to all lights on that side.

what i would do is contact a volkswagon dealer and see if they have a trailer kit. with instructions. or ask if they can do it

it could happened after washing , i think they have wash the car and some amount of water got in side of fuel flap sensor , try to clean it, or you have to replace it. thanks.

There really is no way to change just the cover. Open the hatch. There are two quarter sized round plastic clips that have to be gently pulled out. Then you can remove the tail light.

open the trunk and unscrew the plastic nuts on the back side of the light assy and replace

I don't think it has anything to do with the sunroof. I think you have a leak either around the windshield or under the cowl where the wipers are attached. If it's in the cowl area probably over the blower motor housing on the right and the water is following the vent system to the drivers side. Please let me know how you made out.

Thank you

Good day;
In your trunk area there should be a piece of carpet by your tail light just move that to the side and then you can access your bulb. Any problems please let me know.

Cheers