Check the brake light switch.
The probable cause of the brake lights not working on your Renault is the brake light switch. The brake light switch can be found under the dashboard by the foot pedal.
After a repair has been made on a Renault Laguna the service light will need to be reset. To do this plug the diagnostic tool into the computer and reset the light.
try the switch on the brake pedal maybe try the switch on the brake pedal maybe
The reversing light switch on a Renault laguna is in much the same as on many other cars. Basically it links to the gearbox or the gear lever, so that when the gear lever is at the reverse position it engages the switch. On the laguna it is on the gearbox near to the left hand end (from the drivers view). You must remove the left front wheel to see it more clearly and possibly the plastic under-engine plastic shield. The switch is normally open, and shorts out when you engage reverse, so you can test it with an ohm meter.
its the tyre pressure sensor
where is brake light switch
changeing side light bulb
Behind front off side light in engine bay, in Laguna 11 Hatchback 1.8ltr
How to remove drivers' side light cover
You can try to reset your brake light switch by unplugging the brake light switch and plugging it back in. If that does not solve your problem you will need to replace the brake light switch.
a switch that is trigered to light up the light when the brake pad is pushed in