Swap it over to the other side to make sure it's not another faulty bulb.
If not, check the fuses (700cc Fortwo, 451, Roadster)
Still Doesn't Work! (Or The Bulb Is Dim)
Check the bulb connector with a multimeter. There is a chance that with
the headlights on, you will still get a reading of approximately 12 volts.
Why Is This?
Quite a few smarts suffer from burnt connections at the fuse box. A poor connection due to
over wattage bulbs or poor quality bulbs causes an increase in arcing at the fuse box connector.
This arcing causes heat which damages the connection and increases electrical resistance.
Voltage can usually get through but there isn't enough contact to allow
enough amperage through to actually light the bulb sucessfully.
What To Look For?
Drop the SAM unit down and check the nearest connector. N11-3, it's brown.
Look for charring, burning, overheating or any damage. Thanks to Piers M for the photo.
The 4 wires that feed the lights are shown below.
450 & Roadster
1 - Grey/Red - Left Low Beam
2 - Blue/Green - Right Low beam
3 - White - Left High beam
4 - White/Blue - Right High beam
1 - Grey/Yellow - Left Low Beam
2 - Grey/Violet - Right Low beam
3 - White/Black - Left High beam
4 - White/Red - Right High beam
What's The Fix?
Smart will sell you an N11-3 repair kit which should consist of the plastic connector with
terminals fitted and a short length of wire coming from each. You are supposed to cut the existing N11-3 plug off and crimp the new one in place but there is a slightly better way of doing it.
Remove all the terminals from the old plug connection and bin it, it's burnt so no good.
Remove all but the corresponding burnt wire from the new connector. Plug all the old leads into the new connector housing, cut back the burnt wire and crimp the problem wire to the new connector.
The N11-3 12 pin brown SAM unit connection repair kit part number is: