Hazard warning lights won't turn on, w140

[Strawman]

I've replaced the switch as that was broken but they still don't work, everything else does, indicators work off the stalk, alarm turns them on. This is the only thing the car failed the MOT on so is quite a problem for me. The car is S280 W140 from 1994.
There is power to the switch, and the switch illiuminates when the sidelights are turned on. Thanks in advance.

 

[NW_Merc]

Check the relay, now I have a 202 so I cant tell you if it is the same, the relay is in the boot in my car, next to the battery.

 

[Dec]

Not a W140 below but I think you might have an N10 relay, are you sure the indecators are fault free.
http://forums.mercedesclub.org.uk/sh...ad.php?t=62702

Dec