I have a 1997 (P) c180 and my horns don't work, so i have replaced both horns, and checked fuse and they still don't work. I was told it may be the horn relay, so i have purchased the relay from merc and i cannot find where it should go on the car..

please help MOT in 4 days....

Thanks

Dave

 

Most of the relays are in the main fuse box, located at the rear of the engine compartment on the left hand side. Additional relays may be located in the module box located at the right hand rear of the engine compartment or in the luggage compartment, near the battery.
To gain access to the relays in the engine compartment, the fusebox cover must first be unclipped. Remove the screws securing the fusebox cover surround and lift off the larger cover.
If a circuit or system controlled by a relay develops a fault and the relay is suspect, operate the system: IF the relay is functioning it should be possible to hear it click as it is energized. If this is the case the fault lies with the components or wiring of the system.
IF the relay is not being energized (no click), then either the relay is not receiving a main supply or a switching voltage or the relay itself is faulty.
While some relays look the same, and in operation, others look similar but perform different functions.