3rd brake light

[Deleted member 138290]

Well I’ve had no 3rd brake light for a couple months now..... I’ve tried everything that’s advised on the net and nothing..... no other light issues just the 3rd....... could the brake light switch be at fault ? Tho it’s only a year old..... but today I realised that it’s when I hold the pedal down for 3+ secs and the warning comes up on the dash.... it’s 2003 e320cdi saloon..... any ideas please ?

 

[OneForTheRoad]

Chances are the leds circuit board is goosed.

 

[Deleted member 138290]

Sorry ment to mention I changed the brake light, infact 3 to be exact as I kept breaking them in half trying to fit them...... so the original light wasn’t the issue ..... but it’s got me beat what the problem is....

 

[mercmancdi]

You may be right , I had a pain with a brake light switch on s class it messed about until I bought a cheap after market and it solved a few problem. But i am no expert

 

[Deleted member 138290]

I will try another switch and see what happens

 

[markmifsud]

broken wiring at the boot hinge?

 

[Deleted member 138290]

Already fixed the wire, that had been previously fixed.......

 

[markmifsud]

have you checked the repaired section to see if you are getting +12v when you activate the brakes?

 

[Wolfie1]

Wont be brake light switch if the other 2 work

 

[inthegarage]

Wont be brake light switch if the other 2 work

Just a thought, take a feed off of the brake lights that are working, do away with the feed to the 3rd light

 

[Benzmanc]

Just a thought, take a feed off of the brake lights that are working, do away with the feed to the 3rd light

doing that will show a canbus error

 

[inthegarage]

Not always on older models. I fitted DRL on my 2000 car taking a feed off the sidelights for the switching relay. No canbus error, must be worth a try nothing to loose

 

[David404]

Already fixed the wire, that had been previously fixed.......

I've now repaired the wiring in the boot hinge on my 2009 W211 3 times! and I'm not the first to repair the wiring. As another poster suggested get a meter on the brake light to see if its getting 12V.

 

[Deleted member 138290]

Hi all ! Yea fitted the new switch on pedal today and still same problem..... funny as mentioned as I did find that where all the wires are joined behind the boot lid cover that only the single wire to the 3rd light didn’t have power to it ?? As my test light didn’t light up ???? Yet all the other s it did when I touch the connector....... I will try a feed off the side lights if I can work out how to bypass via switched relay.... otherwise I must have a corroded/ broken wire or bad earth somewhere..... also I’m still getting battery drainage after just 10 mins when anything is running off just the ignition..... been the same ever since I bought the car 18 months ago.... diagnostics does show fault with 3rd stop light, open or short circuit... fixed the other faults it had then got random blocked wiper motor relay ????

 

[Deleted member 138290]

I will also get a multi meter tomorrow if I go into town,

 

[Deleted member 138290]

So, turns out there are different sizes to this 3rd brake light ie.... from lens to bottom of black bracket with led strip varies from 34mm-61mm so I must have bought the 34mm by mistake hence, doesn’t push into bootlid...... so another £20 just now on a 61mm instead then look into bypassing the wiring, lol wish me luck !

 

[Deleted member 138290]

2047-01

9035

9068

9001

9027

9030

9056

9078

9051

9005

9208/9

9470 r22/3

 

[Deleted member 138290]

That’s all my fault codes listed lol.... crumbs !! Anyway there’s no power from the rear SAM to the led brake light..... or so my multi meter said lol... however does anyone know where the 2 wires go from the brake switch ?? I can see they go into loom under d/s footwell but it started raining so had to call it a day.... also swapped the d/s mirror control today and up/ down drs door still not working so I’ve got serious electrical issues..... but then I’ve had something draining the battery since I’ve had the car as it came up battery convenience temp unavailable the 1st time I did a job on the car and had the radio on as you do lol.... anyway any help/ advice would be very very much appreciated at this time

 

[Deleted member 138290]

Looking bk at prev reply’ s I should maybe move the live wire from the n/s brake light to the sidelight and see if that does actually cure the error ? Lol then just got to sort all the other issues

 

[Deleted member 138290]

After yet more reading/ research regarding going thru the fault codes It seems it could possibly simply down to the alternator not giving enough charge.... thinking about the V current was maxing at 11-13 with engine running but didn’t check whilst engine off ....