Hey Crossfire Gang,

My name is John. I literally joined this forum to hopefully get some advice from more experienced crossfire owners. I love my coupe.

I have a 2004 automatic crossfire coupe (saphire silver :-))
And recently I noticed that all of my brake lights do not come on.
All other lights work fine. No other issues at all. Signals are good.
I also noticed the bas esp light come on only when i press the brake pedal down it will pop up and stay up until i shut off the car. (Then it goes away, until i press the brake pedal and it again pops back) i know its obviously due to the brake lights.

First thing i did was check the fuse #2 in the inside fuse box. It looked like it was okay. Is this the correct fuse? A little discoloration but the wire in the middle was in tact.

Any ideas on what this could be?!
Times are a little rough right now, so i cant really afford a expensive fix, especially since i recently shelled out 800$ for brand new tires!

Any one who has some ideas on what this could be, id greatly appreciate it!!!

Thank you all.

 

Do you have a multimeter? If so, test the BOO (brake on/off) switch. Fairly common on the R170, W203, W211 chassis on the Mercedes side and we all share the same switch.

 

You must get the codes read and see if any have been set. This should indicate why the light is on.
I do not think it has to do with the brake lights, but who knows on this one.

 

Is the center stop light working? If it is, both your bulbs are blown. That's LED and doesn't usually have a problem. If that's not working as well, it's definitely something electrical and probably would be the brake light switch.

 

Fuse is a big square, on the drivers side of the engine bay, on the lower level of the fuse box. There should be 2 square fuses, the one which is closer to the center of the car is the one...at least that is what I have read in this forum

 

Hey Guys,
Thanks for all of the responses. The top Led light is not coming on as well, so im thinking it can be the light bulbs are bad. It doesnt seem to be a fuse. I went into the fuse box on the inside of the car and pulled out fuse #2 which in the manual says, it controls "break lamp/speed control". I took the fuse to autozone to have them make sure fuse #2 was good and he assured me it was. Told me that it may be that all 3 light bulbs have died. He said when one goes sometimes it can trigger all of them. Then again he didnt know i had a crossfire and the top brake light are LED lights. Is this possible?

Since it doesnt seem to be the fuse, i may have to take this one in to the mechanic. Hell probably rip me off but what can i do? 😒😒😒😒

Are there any other fuses that would be involved with the brake lights, under the engine hood or inside. Just trying to make sure i checked everything before i go to the grim reaper me hanic in my neighborhood.

Thanks everyone.

 

AIG thank you.
So if it happens to be the brake light switch, any idea on how much a repair like this qould cost me? Ive never heard of a brake light switch so im clueless.
Thx

 

ImportlabSrt i dont have a multimeter buddy

 

Edit
I just looked at the time line and I guess you have not looked at the switch, the switch is at the top of the brake pedal or on the master cylinder.
If not the switch the problem probably lies in the brake lamp relay.
The brake lamp relay is what the post above is referring to, it is not a fuse. when the brake pedal is pushed you should feel this click. You need a helper or long arms to do this.
If the other relay beside it has the same part number you could possibly try the other relay and see if that solves the problem.
BRAKE LAMP RELAY
DESCRIPTION
The brake lamp relay is located in the underhood accessory fuse block in the engine compartment. The brake lamp
relay is a micro relay and is contained within a small, rectangular, molded plastic housing. All of the required inputs
and outputs are connected to 9 blades that extend from the bottom of the relay base.
OPERATION
The brake lamp relay uses a low current input from the illumination control module to control a high current output
to the brake lamps. When the relay coil is energized, an electromagnetic field is produced by the coil windings. The
field draws the moveable relay contact point away from the fixed normally open contact point and holds it against
the fixed normally closed contact point.
The brake lamp relay terminals are connected to the vehicle electrical system through a connector receptacle in the
underhood accessory fuse block.
REMOVAL
1. Disconnect the negative battery cable.
2. Remove the underhood accessory fuse block cover and
relay cover panel.
3. Pull upward on the brake lamp relay (1) and remove it from
the underhood accessory fuse block.

 

Onehundred thanks for your knowledge!
Okay so i got down under the sterring wheel and looked up and i can see the plunger looking onject and the brake is pushing towards it. Its kind of hard to get into that area but what should i be looking for exactly? Perhaps i should take a look at the relay since its easier to get to? Its the yellow one? Should i remove the connection and try and replace it with another thats the same number?

As you can tell im horrible with cars other than basics. Im greatful for your advice. Sorry to be so dumb!! Lol

 

If the switch is under the dash on the brake pedal it looks like the sheet below.

You should down load the 2004 Service Manual from this site (Click) here.

Does the relay click when you push the brake pedal?

 

Onehundred,

I just went out to the car to check and see if i could hear the click and sure enough it does click when i press it down.

What does this mean?

Thank you again dude.

 

And thanks for the manual. Im saving it

 

I am getting out of my depth here. The relay is working so power is going to the light switch. The light switch is referred to as the Illumination Control Module in the Service manual. Presumably the power is not coming out of the switch.
Have you or anyone else been into the back of the switch area? It could be possible that the plug that goes from the relay to the light switch is loose. I have seen a situation where the lights went out suddenly when a plug came loose as it had not caught on the catch on the switch.

There are four plugs that plug into the light switch and you should check that they are all tight.
The ABS system is somehow involved with this relay, brake switch and light switch.

The power comes from and returns back through the light switch on its way to the brake lights.

Look at 8W-51-3 in the service manual for a circuit diagram.

 

Okay thanks bud,

Ill try to get back there tomorrow and check all of the plugs to see if anythings seems loose. Appreciate the advice.

 

Like said above....you can try swapping relays. If the lights still do not work, my money is on the BOO switch. I worked at Mercedes for 4 years and replaced dozens of them on other chassis with the same part number switch.
In a perfect world, you would have a multimeter or at least a test light and I could walk you through a few steps to diag. Main thing is to see if you have voltage coming into the BOO switch and voltage out when the plunger is depressed. If you have voltage out, then next would be to check the relay.

 

The OP says the relay clicks when the pedal is depressed so I would imagine the brake switch is working. That's what I see from the circuit layout. If power is coming out of the relay to the light switch is a different matter.
If the plug is pulled from the back of the light switch then power should be evident at pins 2, 6,5 and seven when the pedal is pushed. If power is found only at pin 2 then the light switch is faulty.
That's my guess anyway.

 

So did you ever figure out the problem?