Outlawlatemodel

Hi just want to get the dash lights warnings to go away. car runs good shifts weird. I dont think there is a brake light switch on the pedal on a 06 im pretty sure its a pressure sensor. by the master. I even bought one to have on hand before i took the panel out but to my surprise i was sold a switch for a car that doesn't have one. I believe it is the scanner i have seems to work ok has gotten me in a direction I just need to down load the codes chart and go at it. I was hoping someone else had fixed these problems so i wouldn't have to trouble shoot further.

I do understand what your saying about the switch. The problem is they are off until you turn on the headlights. either i have a bad relay or possibly a cut wire or a bad switch, i need a wiring diagram.

knowbenz

Yeah, did you check the stop lamp switch?
So, if you had an SDS or took it to somebody that had one you could check the actual values in the various modules to see if the stop light switch is on/off, perhaps it is stuck on due to internal short. Perhaps the rear SAM has water intrusion and short caused lights to stay on. Stop lights is a fairly simple circuit

Outlawlatemodel

Yes they are sir, the sam has been replaced, I could go for your idea of the switch sounds great, but it would come on when I started the car and it doesnt. The brake lights come on when you turn on the head light switch so there is a cut wire or or burnt wire or someone plugged a wiring wire in to a connector

Unless it is back feeding through the pressure switch or some one crossed the wires, hmm ill look this weekend

knowbenz

The front SAM was replaced or rear SAM? These cars aren't wired the way it appears you think they are. Throwing parts at it until it's fixed is the wrong way to go about it. spend the $100 for diagnostics and save some money and headache. Most independent shops will roll the diagnostics into the repair. Stop light switch is wired to ESP module and then the data gets transferred through the engine CAN Bus into the EIS and from there goes on the body CAN to make its way to the rear SAM. Its not like there are two wires from the switch to the lights in the back. So without proper diagnostic equipment and guessing at what part to replace you could need any of the following,
Stop lamp switch
ESP Module
EIS
Rear SAM
tail lamp circuit boards.
Or perhaps the car has been ran through so many DIYers that somebody tapped into the wrong wires at one point with some aftermarket equipment.

Are there any messages in the cluster about bulbs out? The brake light bulbs also function as tail light substitution bulbs if the tail lights are burned out.

Outlawlatemodel

Thanks bro, i like your armature statement, kind of nasty dont you think. first you have not said anything I havent all ready checked, but thanks anyway.

knowbenz

Then take it to the dealer. I don't understand what you are trying to accomplish at this point with this thread. You can't check voltage on a CAN line and know if the message is on the bus or making it to the rear SAM. You need an SDS to aid in diagnostics. I'm not sure which part of my response you think was nasty but it wasn't supposed to be. When I read your response it seems as if you are thinking to trace the signal with a test light. Also the question about messages on the dash is another you didn't answer.

Outlawlatemodel

My scanner does read the can, so not sure what your saying. The local Mercedes VW dealer has a tenancy to create work as in took my daughters vw in for tranny fluid change they took a screw driver and punched a hole in the water goose neck, i have taken mercedes to them with the same results next dealer is 125 miles.. not sure why you keep involving yourself, NO ONE CAN TELL me that cars dont have the same problems per model, as in the air bag for this car. do you work at a dealership? if its within a 500 miles i may ship it to you, i have read post after post with the brake light problem yet it has never been solved. You seem to be a nice person, I just dont understand why you insist i take it to the local dealer when I am simply asking other members if they have had this problem. If there is a problem with me asking other bbs members these questions ill take this post down. But then again what value would this bbs be if every one that ask a question was told to go to the dealer?

Russell Ormerod

It is true that the same problems do occur on the same models.
But that does not mean your issue is common!
But could be a rare issue or even a man made one.

If you are going to fix this car you need to diagnose it properly and to diagnose it properly you need a good understanding of how your brake lights function from the input to the output stage.
So instead if guessing and testing things that don't relate to your problem
Go find a wiring diagram and trace the circuit.

Here is a tip to start you off.
1.did you look at the brake contact in actual values in ESP
2. Is there aftermarket wiring to a towbar
3. Did you disconnect the can bus to rear Sam and check if brake lamps go off
4. Did you look at actual values in rear Sam to see if brakes are on?
5. Did you bother to look at the wiring diagram and check the BLS input to rear Sam.

Good luck

knowbenz

I keep telling you to take it to the dealer because I sense a lot of hostility in your posts. I have no idea what kind of scanner you have based on the generic codes you originally posted. Simple questions have gone unanswered that may help narrow down what the problem is. There is a path the data takes to end up turning the lights on. If you have a generic scanner it may only read generic CAN data and not manufacture specific data. These are things I don't know because I only use SDS for diagnosing issues with Mercedes Benz. I have worked in dealership and independent shop since the w203 chassis was introduced. Its hard enough to diagnose a problem online and even harder to do it with limited information provided. If you need help I can provide help but more information is needed. Here is a function diagram of your brake lights which may or may not be useful

knowbenz

Do all 3 brake lights stay on or just the left/right?

Does you scanner read any stop lamp switch values in any module?

Can you use your scanner to perform activations of the stop lamps?

Do stop lamps function properly with the lights off?

Do you get any error messages on the dash when the fault occurs?

What year is the car?

Sedan/coupe?

I would think the reason so many posts go unresolved on these forums is because the average DIYer doesn't have access to proper diagnostic equipment and if they do they don't fully understand what goes into the various systems they are attempting to diagnose.

Outlawlatemodel

Hi guys I havent had much time to look at it. I traced my steps back, the third brake light works properly. When I got the car the brake lights were on, so I did like anyone else, went to the local parts store and replaced the bulbs with no different out come. So I decoded to go the local Mercedes dealer for bulbs exactly the same outcome. I got to think what if the local dealer which I know does a poor job sold me the wrong bulbs na cant happen. So today looked up part number on line and is a total different number that the parts store gave me. no Idea what number mercedes sold me as there is not a part number. Anyway the brake lights are off but now they dont work when depressing the pedal. The third brake light works.
So you have mentioned take it to the dealer, if they cant figure out a bulb i am not taking it there

KnowBenz I wasnt expecting the dealer to sell me the wrong bulbs chased that for several months. They are know cons will not go there. under what system would the brake lights code be under on the reader. I am leaning toward the brake light switch on the booster as there is not a switch on this car. Thank you

Russell Ormerod

Your logic should tell you that if the third lamp works it cannot be the switch! You can read the faults in the rear Sam. As long as its a 21w bulb it must work. It does not have to be a specific number. Possibly your rear Sam has failed!

knowbenz

So wait, do they not come on at all now? I thought the problem you were chasing is that they are stuck on.
Are there any messages displayed in the cluster?

Outlawlatemodel

It looks like the previous owner put the wrong bulbs in. I went to the local parts store and bought new bulbs, no change so I went to the MB dealer and bought bulbs the lights stay on. So I look else were. Go to thinking what if the dealer sold me the wrong bulbs SURPRISE they sold me the wrong bulbs . Now the tail lights work correctly no brake lights the auxillary brake flashes now, the third brake light does work not sure if it is on its own circuit because it has its own wiring going into the sam. I think I am going to have to look at a wiring diagram it this point. I could jump the wiring from the third brake light and make it light but it would be nice if the dash left and right dash light would go out. on my reader i have to figure out whitch one reads the read codes.

knowbenz

If you need wiring diagram or anything I can help you out but I'm starting to get confused about the exact problem. What exact messages are being displayed? You previously said the SAM has been replaced but did not specify if it was the Front or Rear SAM.

Outlawlatemodel

here are the codes I did not write down what it says like can 30(not sure what a can is) I do think the battery needs to be replaced as a few things read low voltage. Sorry it has taken so long in the middle of a huge project.

esm module I know this car does not have the updated harness or bag replacement
91c3
9123
9203
9143
9103
9183
9163
9003
overhead
b1001
b10c0
b1066
ucp upper
9028
9035
Front sam
b1029
b1030
b1049
b1050
b044
Rear Sam
B1044
B1054 it did say stop short circuit
B1047
B1055

i BELIEVE AC
1653c

not sure b1010
9010

Any help is greatly appreciated I am willing to sell whole cars as the motor has 55 k

Outlawlatemodel

Rear sam was replaced with a known good used part

knowbenz

Yeah I'm not about to look up all those codes. Are there any bulb error messages displayed on the cluster or not?

Outlawlatemodel

Yes it say rr and lr brake lamp. I know it goes to the top light in the housing and flashes any place to find know brake code? Thanks in advance

knowbenz

What flashes? the brake light? I wouldn't be that concerned with the code at this point. If you have a message on dash then the SAM is picking up a fault within the circuit and shutting it off. 21W bulbs? make sure the boards aren't shorted

knowbenz

E21 in second pic is 3rd brake light

E3/e4 is stop lamp on left side
E4/e4 is stop lamp right side.

Outlawlatemodel

Any chance you have a chart on what bulb goes where,
two bottom tail light?
Very top brake light
middle backup reverse

Brake lights does light and turn off
is there a common short on these, i did replace both bulb carriers again i can not tell you how much i appreciate your effort, it restores my faith in this bbs, Thank you ==Kevin

knowbenz

Yeah, if you look on the board it should have stamped the wattage of the bulbs. Turn all other lights off and look to see if any other lights flicker when the brake lights come on momentarily. I've seen a lot of carriers melted and it will touch one of the other bulbs contacts and light both when you step on the brake. Since you said those have been replaced I would just make sure you have 21W bulbs at the top and then start looking into the wiring. Loose ground perhaps, possibly tight enough to no effect the other bulbs but loose enough that when all the lights are on then the little extra juice from brake lights is enough to shut them down. If it were both sides happening at same time then perhaps something in common like the ground. Make sure nobody tapped into any of the wiring running to tail lamps.

You could also try unplugging the boards and see if one side works, then swap sides to see if other side works.

Outlawlatemodel

I have replaced both carriers, i inspected the wiring between the same and the carriers and there was no sign, if the top bulb is indeed the brake light, it flashes a couple times a seems to loose power.

knowbenz

When SAM detects open or out of spec resistance (wrong bulb) it will just shut down that circuit. If indeed the SAM is good, carriers are good, and bulbs are correct then you have a wiring issue.

If the input to SAM for brake lights which is coming in on CAN Bus was not there or cutting out you wouldn't get a bulb out message on the cluster. If the 3rd brake light functions normally then you also eliminate all inputs as a possibility

If you are confident the bulbs, SAM, Carriers are good then dig deeper into wiring, loose pins, high resistance, slight short to ground from rubbing through somewhere, loose ground, loose pins at SAM or the carriers. This entire drag shouldn't take more than 30 minutes tops.