I's not the brake light - it's the "park" light (lower section of the lens). My recommendation is to replace all of the bulbs in both tail lights. The SAM determines if the bulbs are functioning based on current draw. I have seen a set of old bulbs cause erroneous messages. Replacing them all fixes this. And also check the bulb sockets to make sure there is no corrosion.

 

Replaced the park light and there's no more malfunctions, thanks!

 

So I replaced all the bulbs (on the left side except the reverse and signal bulbs) and the message stays clear. Now every 2 or 3 times that I start the car the message comes on again. Anyway to clear this? I don't know if it's electrics or if it's one of the reverse or signal bulbs?

 

TBH, I've had my clk 500 for almost 3 years now, and I have given up on that error message, I've changed every bulb on the car, and even taken fine grit sandpaper to every socket, sometimes the message goes away, then back a few days later. All my lights work so I said F it.

 

I've had this problem on the C240 and have always solved it by replacing all the bulbs on both rear assemblies.

 

Like the problem really isn't a problem, but just having the message show up on my car every few days is annoying. I guess I'll try changing every bulb on the rear lights and see what happens. Going to the dealer for this would be stupid (they'd probably charge me like 200 bucks [they tried charging me 200 bucks for the third brake light when it fell off and it was from a totaled CLK LOL]).

 

So, I had the same message for a long time and today i decided enough is enough. I look at my tail lamps and both are on, so no reason for the message to be on. But then, when I took all the lights out I realized the problem. The regular tail lights are on the bottom, the ones with 2 fillaments even though only one is ever used, and the back-up tail lights (back-up as in spare not back-up as in reverse) that are meant to come on when one of ur regular lights go off are on TOP. So looking from the back of the car i never realized that im looking at the back-up lamps (once again back-up as in spare, not backup as in reverse) So if you have the message that your back-up tail lamps are one, look to see if when u turn the lights on the ones on the verry top come on or the ones on the bottom. If the top set comes on (those are your spare) then one of your bottom one is out. In case i sound confusing.... the top lights are the verry top lights, and the bottom are the verry bottom lights....... top set of lights are above the reverse lights, and bottom set are below the reverse lights.... just wanted to make sure everyone understands.

 

I will have to look at this when I get home... sounds interesting. Might be why I was getting errors when switching bulbs?

So the very bottoms should light up and then the tops only being brake lights when the pedal is pressed right?

-Nigel

 

That's correct.

 

Check you owner's manual:

#8 has a single bright bulb that illuminates when the brake pedal is pressed.
#10 has three bulbs, two rear-facing, on side-facing.

If you will notice, the bulbs for #8 and the two rear-facing bulbs for #10 are P21 type, which are dual-element bulbs. Park lights are lower intensity than brake lights. So, if the #8 is the brake, and the #10 is the park lights, why do they all need two filaments for both high and low intensity? Well, it is so they can "multitask" if needed.

The rear SAM can detect when a bulb is out, and if so, it will use a different bulb to replace it. When it detects that a brake light bulb (#8 ) is not working, it will use the high-intensity filament for the park lights (#10 ). When this happens, you will get two error messages: one tells you the brake light bulb #8 is out, the other tells you the "spare" bulb (the high-intensity element of #10 ) is being used instead. Also note that #13 is listed as a rear fog light. In reality, the rear fog light is just the high-intensity filament of the inner park light (#10 ) bulb. It is activated by pulling the headlight switch out to the 2nd position (1st position is front fog lights).

 

Check you owner's manual:

my brake lites are # 10 and tail lites #8 on my clk 500 any idea why?

#8 has a single bright bulb that illuminates when the brake pedal is pressed.
#10 has three bulbs, two rear-facing, on side-facing.

If you will notice, the bulbs for #8 and the two rear-facing bulbs for #10 are P21 type, which are dual-element bulbs. Park lights are lower intensity than brake lights. So, if the #8 is the brake, and the #10 is the park lights, why do they all need two filaments for both high and low intensity? Well, it is so they can "multitask" if needed.

The rear SAM can detect when a bulb is out, and if so, it will use a different bulb to replace it. When it detects that a brake light bulb (#8 ) is not working, it will use the high-intensity filament for the park lights (#10 ). When this happens, you will get two error messages: one tells you the brake light bulb #8 is out, the other tells you the "spare" bulb (the high-intensity element of #10 ) is being used instead. Also note that #13 is listed as a rear fog light. In reality, the rear fog light is just the high-intensity filament of the inner park light (#10 ) bulb. It is activated by pulling the headlight switch out to the 2nd position (1st position is front fog lights).

 

Long time lurker here. Should've been more diligent in using the search function to resolve this problem.

When I saw the "back-up" light malfunction, yet the reverse lights were working, I assumed I had a short in bulb bracket. So now I have an extra one (left side).

I'm re-bulbed (on both sides) now. All is well. Thanks to all for the good info.

 

Does anyone know the OEM bulb that this should be? I would hate to get the wrong one and cause even more problems.

 

See diagram post #11 above, for bulb types. Rear parking lamp bulbs #8 ,9 &11 are the same P21W only #10 requires the P21/W4.

 

Just to warn everyone who does not do a full re-bulb, you my reach the wrong conclusion; so read this. First, probably repeating what 's been said above: If you get a left or right tail light out warning and the backup light used warning, then the rear sams unit will do a switch so you get the top brake light sections used as tail lights. The sams box tries to keep the lamps symmetrical so it switches off the good side too. However you may find that you change the tail P21/5 bulb(s) and the 21W stop bulb(s) and the problem does not go away. Replace the small bulb next to the P21/5 bulb and mine was OK. On my 2002 CLK it is a R5W and not a W5W as in the diagram above.
(For me this simple issue was a long trail and I bought a used rear sams unit to no avail before I got there).

 

Not unless you use "error free" or "CAN bus ready" bulbs that draw the same wattage that the SAM expects from the halogen bulbs. Improper bulbs won't harm the SAM, but bulbs with a different current draw (like lower wattage LEDs) will cause the SAM to throw an error and shut down the circuit.

 

Got it thanks.

 

A bad bulb won't drain the battery, but a bad SAM could.

 

All my lights front and rear are not turning on .The front lights only turn on when I switch to bright mode and the rrea lights remain of but the bulbs are new ,what could be the problem with my c200 kompressor