On 2003 vw Passat my tail lights won't come on but

Have you checked the bulbs and fuses? The fuse box for them is under the bonnet, usually near the battery. The lid normally just unclips. Try fuses 13, (brake lights), 22 (right), and 23 (left) for the tail lights. Always replace fuses with the same colour and rating.
I think on your model the bulbs are fairly simple to get to. Fold the small cover inside the boot out of the way. The bulb board is simply clipped into place. Bend the two clips inwards and wriggle it out past the boot liner. The bulbs are just a small turn Anti-clockwise and It slides out.
I've attached links to a fuse box diagram and a YouTube video for the rear lights.
https://fusesdiagram.com/volkswagen/fuses-and-relay-volkswagen-passat-b5.html

https://youtu.be/fHxaLhpWM0s

• If there are no brake lights period the check the stop switch (brake light switch)
• This is attached to the upper part of the brake pedal itself. Should be a little wire off of it. When that goes bad the brake lights will not work at all.
• Please note that the fuse for "brakes" is ABS only and has no bearing on the brake lights themselves working.

Regards, Tony

Hello, Well there is not much more it could be unless you have a shorted wire or a burned fuse. I would normally think that the turn signal canceler was bad but the 3rd brake light will still work if that is bad so I would check all fuses and for bare or shorted wires.

check to make sure that you have the correct bulb in the correct socket in both left and right tail lights. dual filament bulbs have to contacts on the base of the bottom of the bulb. make sure the socket that you are inserting them into also has two contacts. if that doesn't work then you need to get a test light so you can find out if power is going to the bulb housing and all ground. check all fuses also with amp meter

check the bulbs ofcourse but also check the wiring harness at the conectors

The brake pedal whenever pressed open the circuit to complete the circuit which turns on the brake lights. Its like if the brake pedal is not depressed the circuit is bypassing the light. So when this short-cut is opened current has to go via the tail; bulbs making them glow..........sodeep

Yes, check the fuses. It should tell you which it is on the fuse box cover. Or you could just pull all the fuses out. Also you may have a loose earth connection.

most rear tail lights and turn/stop lights are the same dual filiment bulb. it is possible for your tail light to work and your brake light not to and still have a bad bulb. I would check the bulb first, your brake light works on the left yes? this would mean that the fuse is fine

Rear lights are double filament bulbs one side for the lights other side for the brake/turn signals so it still may be a bulb. Do u have a test light or volt meter you can check to make sure u have power there when brakes or turn signals are activated. Or just try another bulb.

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