Why stop sign lights?

If you mean 'Why does the stop light on my Peugeot 406 light when the hand brake is not on?' then here are some possible reasons

1 check the fluid level in the reservoir under bonnet

2 check that hand brake is functioning properly

3 check rear wheel cylinders for leakage

4 check brake shoes for wear

5 check the brake adjusters

Most likely reason is that the shoes are worn and/or the adjusters are not functioning which can lead to leakage from the rear wheel cylinders. Brakes may still work but if there is excessive play on the hand brake this is a good indicator that the adjusters need tensioning

Rosignol