How to troubleshoot non-functional brake lights on an Audi 80?

The brake lights on my Audi 80 have suddenly stopped working. I have checked the fuses and they seem to be in good condition. What steps can I take to diagnose and fix this issue?

First, check for any loose or damaged connections in the wiring harness for the brake lights. If everything looks good, use a multimeter to check for power at the brake light switch and at the bulbs themselves. If there is no power or a weak signal, it may be a faulty switch or relay.

Sometimes, dirt and debris can build up on the contacts of the brake light bulbs, causing a poor connection. Remove the bulbs and clean the contacts with a fine-grit sandpaper or a specialized electrical contact cleaner. This may solve the issue without needing to replace any parts.

If the brake light switch is not functioning properly, it may need to be replaced. This is a relatively simple and inexpensive fix that can be done at home with the help of a repair manual. Just be sure to disconnect the negative battery terminal before starting the replacement process.