Checking brake lights (Audi A4 B6)

1. Check the brake light bulbs, replace if necessary. If the bulbs are OK, check the brake light switch. When the brake pedal is pressed, the switch closes and the lamps light up.

2. Check the brake light switch. The switch is located in the foot area, on a support, at the top of the brake pedal, refer to Section Removal and installation of the brake light switch.

3. Turn on the ignition.

4. Disconnect the brake light switch connector and connect the plug contacts with a short auxiliary wire. If the brake lights now come on, the fault is in the switch. Replace switch.