mis3

I recall I read something about standby light bulb in the rear bulbs holders. There was a thread about this but I can no longer find it.

From the owner manual, there should be 5 functioning bulbs: brake, turn signal, backup, standing/side marker and tail. Where is the standby bulb?

Rudeney

The park lights use a dual-filament bulb that can be used in place of a burned-out brake light.

mis3

How does this work? Do I have to manually swap the 2 bulbs?

Kustom1911

In Germany they call parking lights, standing lights or stand by lights.

On a CLK the # 4 bulb is the standing & Side marker bulb or standby bulb.

Rudeney is correct it is a dual filiment bulb that the rear SAM can use the 21W side as a backup brake light if needed.

My wife has a 2004 CLK500 and in her manual on page 351 it describes the bulbs sort of.

I learned a lot about how they work when she was out of town and the dealer wanted to replace the rear SAM unit, and all that was wrong was it needed a correct tail light bulb when she got back home.

Hope this helps

mis3

Sorry, still not clear.
If the brake bulb fails, should I manually swap the bulbs (brake and parking bulbs) or not?

I also checked my owner manual, it does not say anything about replacing the brake bulb by the parking bulb.

Kustom1911

If either of your brake light bulbs burn out, a malfunction warning will appear in your dash telling which side is bad.

Your rear SAM unit will use the 21 watt side of the parking or standing / marker bulb as a temporary brake light, until you replace the burned out brake light bulb. The malfunction warning will be on every time you start the car until the bad bulb is replaced.

Beware of cheap replacement bulbs, as the SAM unit checks each bulb for the correct wattage each time you start the car. If not correct after 4 seconds the SAM unit shuts off that bulbs circuit and shows the malfunction.

It is always a good idea to use good quality bulbs and replace both left & right sides together, so the wattage is the same.

Rudeney

No manual swapping of bulbs needed - the SAM figure out a bulb is dead and then electronically substitutes another bulb (or filament) for that function. Of course when this happens, you get a message on the cluster's MFD and thus should replace the bad bulb when possible.

mis3

I am clear now.
Thanks all.

mis3

I asked my buddy who works in MB for a brake light and he gave me one with dual filaments. I guess that SAM will just use the 21W filament then.

Kustom1911

My wifes 2004 CLK500 uses a Osram # 7506 as the brake light bulb which is single filament. Same bulb is also used in the backup light and turn signal positions.

The only dual filament in the rear lights is the left rear fog light / tail light in position # 5 in the owners manual, this bulb is Osram # 7225 and has the insertion prongs at approx. 150 degrees offset.

your OP asked about the standing lights. Do you have a brake light issue now?

The specs for these bulbs are on the Osram.com website in Germany.

This info pertains to MY 2004, YMMV.