Replaced BRK SWTCH, BRAK LT CIRCUIT still!

[Jon K]

Ok guys so i got on my floor and replaced the brake light switch... noticing that the old switch had a red sliding tab and the new had a white sliding tab... the unit itself is black. i ordered from bma, they are usually pretty good with part numbers, the package said "switch, brake." so in it went. Turn the car on waiting for no chimes.... DING.... BRAKE LT CIRCUIT. F*cking great. Where do I start now? I have Hella OEM Euro tail lights, supposed to not trip the brake light thing... checked them, they are about a year old, no corrosion, the bulbs are... old I think, but I am not sure. Oh please someone tell me that there is some step im missing or something, im so tired of not being able to use my dash OBC read out!

[Warren N.CA]

where it loops around the hinge. That area is subject to wear by flexing, each time the trunk is opened.




QUOTE=Jon K]Ok guys so i got on my floor and replaced the brake light switch... noticing that the old switch had a red sliding tab and the new had a white sliding tab... the unit itself is black. i ordered from bma, they are usually pretty good with part numbers, the package said "switch, brake." so in it went. Turn the car on waiting for no chimes.... DING.... BRAKE LT CIRCUIT. F*cking great. Where do I start now? I have Hella OEM Euro tail lights, supposed to not trip the brake light thing... checked them, they are about a year old, no corrosion, the bulbs are... old I think, but I am not sure. Oh please someone tell me that there is some step im missing or something, im so tired of not being able to use my dash OBC read out![/QUOTE]

[Jon K]

where it loops around the hinge. That area is subject to wear by flexing, each time the trunk is opened.




QUOTE=Jon K]Ok guys so i got on my floor and replaced the brake light switch... noticing that the old switch had a red sliding tab and the new had a white sliding tab... the unit itself is black. i ordered from bma, they are usually pretty good with part numbers, the package said "switch, brake." so in it went. Turn the car on waiting for no chimes.... DING.... BRAKE LT CIRCUIT. F*cking great. Where do I start now? I have Hella OEM Euro tail lights, supposed to not trip the brake light thing... checked them, they are about a year old, no corrosion, the bulbs are... old I think, but I am not sure. Oh please someone tell me that there is some step im missing or something, im so tired of not being able to use my dash OBC read out![/QUOTE]


****, actually... i do have a couple split wires there... I bet that was the problem all along!!! argh i will start splicing.

[Paul in NZ]

the switch sets its own position.You do not push the sliding tab down,to lock the switch in place.I pulled my old switch out and cleaned it up and put it back in,and pushed that tab in.Was fine for about 10 minutes or until i had to make a firm stop,(DING BRAKE LT..elect) I ended up destroying that switch,the BMW tech told me off and said the switch sets its own position! :(
He must have been right cos its been fine since! ;)

[Jon K]

Guys... need help. Replaced the switch, BRAKE LIGHT CIRCUIT still fires off on the dash. As suggested I checked the trunk harness, and all the wires seem fine. The tail lamps are new (as of a year or so) Hella OEM euro lamps. Maybe the bulbs are acting up? What bulbs should I replace with? Or did I install the switch wrong? I read the article on Bruno's site when replacing... please help me rid of this error.

[Bill R.]

Guys... need help. Replaced the switch, BRAKE LIGHT CIRCUIT still fires off on the dash. As suggested I checked the trunk harness, and all the wires seem fine. The tail lamps are new (as of a year or so) Hella OEM euro lamps. Maybe the bulbs are acting up? What bulbs should I replace with? Or did I install the switch wrong? I read the article on Bruno's site when replacing... please help me rid of this error.

[Jon K]

Yes, it lights. No corrosion.

[Tiger]

Pull out your light check control near LKM... check for corrosion and reseat.

[Jon K]

Pull out your light check control near LKM... check for corrosion and reseat.

Good idea... going to check...

[Jon K]

Checked it out... i think the capacitor is busted? Though I can't tell if that's the stuff from inside or if its some sort of gel coating...

http://e34.digital7.com/BMW%20Work/IMG_2921.JPG

http://e34.digital7.com/BMW%20Work/IMG_2923.JPG

[Tiger]

Mmm... why not swap it with fellow BMW and see if the unit is at fault? If you put yours into his and his brake light warning goes on... then you know that is it.

[Jon K]

I also checked my LKM... here are pics.... no problems that I can tell.

http://e34.digital7.com/BMW%20Work/IMG_2925.JPG

http://e34.digital7.com/BMW%20Work/IMG_2926.JPG

[Jon K]

Update:

So it was like 34 degrees tonight, I decided to go ahead and get new brake light bulbs to see if it was that simple... i turn the car over and to my surprise i get no Brake Light Circuit message (this is before getting new bulbs). I am decided my car is literally trying to f*ck with my head. I drove about 15 minutes to Autozone with no Brake Light Circuit message. I went in and got bulbs and replaced them in the lot, drove back to school 15 minutes. About 2/3 of the way home i get *DING*... ARGH! So, I am convinced it's a resistance issue... probably with the CCM. Since it was colder in the engine bay, and i think resistance (and electrical circuits in general) are more efficient with less % loss when cold, the CCM doesn't check fail. but when the bay warms up and the resistor packs in the CCM consequentially warm, the % fail is greater and it check fails... make sense? Ie. I think my CCM is failing or at least the resistors for the BRAKE LIGHT CIRCUIT have become too old/tired, does anyone know specifically which resistors are for the brake lights?

[Tiger]

Like I said... swap the unit with someone temporarily to see if it is the problem...

[50 fiver]

Jon, I have noticed the same thing with mine, when cold, no message, as soon as it gets above 60 degrees or so, instant message. It has been on my car since I have owned it. Dealer replaced all bulbs and put 2 switches in and still there. Let me know if you figure out what it is. I think you are on the right track.