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.
under the engine beside the paseneger wheel, blue connector
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.
How do I get to the reversing light switch on a Toyota avensis 2005
its the tyre pressure sensor
changeing side light bulb
Check the brake light switch.
Behind front off side light in engine bay, in Laguna 11 Hatchback 1.8ltr
How to remove drivers' side light cover
Try asking at www.renaultforums.co.uk :-)
Alternator bad or wiring fault to alternator.
Bring to a shop that has an ABS scanner to determine the problem
The reversing light switch for a Honda CR-V is located at the front lower part of the transmission. It is almost at the bottom of the transmission, but up front.