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Annoying Brake Light Circut Failure

4K views 15 replies 12 participants last post by  2003bmw325xi 
#1 ·
I got a 93 325is and on the obc it keeps saying brake light circut failure? It is really annoying. I checked the fuse for the brake lights and the brake light bulbs also but no blown fuse or bubls. Can some one tell me what the problem might be? Could it also be the brake switch under the brake pedal??
 
#2 ·
Originally posted by NyteRyda@Jan 7 2005, 10:51 PM
I got a 93 325is and on the obc it keeps saying brake light circut failure? It is really annoying. I checked the fuse for the brake lights and the brake light bulbs also but no blown fuse or bubls. Can some one tell me what the problem might be? Could it also be the brake switch under the brake pedal??
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Yes, take yours out and get the part number off it, there are two different
switches.
 
#4 ·
Get OEM ONLY. There's a BIG REASON FOR THIS.
Do a search. There was a thread on this a couple weeks ago and it had all the info you needed. OEM vs. bavauto, etc.

The different switches are: 4 pin, and 2 pin. If your car has cruise control, you have the 4 pin. If you do not have cruise control, you have 2 pin.
 
#7 ·
Originally posted by zeaq@Jan 8 2005, 10:16 PM
Yeah i know i have to change the switch...

But only next week i'll bring it to the dealers beacuse of Uni classes.Now the warning is coming on every cold start.




So my question is will it be drivable?I remembered someone here said it's not drivable?
I want to know is it ok for me to drive for another week or so with the "brake light circuit "warning on?
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Anybody?is it ok for me to drive for another week or so with the "brake light circuit "warning on?
 
#8 ·
Originally posted by zeaq+Jan 9 2005, 12:06 AM--><div class='quotetop'>QUOTE(zeaq @ Jan 9 2005, 12:06 AM)</div><div class='quotemain'><!--QuoteBegin-zeaq@Jan 8 2005, 10:16 PM
Yeah i know i have to change the switch...

But only next week i'll bring it to the dealers beacuse of Uni classes.Now the warning is coming on every cold start.



So my question is will it be drivable?I remembered someone here said it's not drivable?
I want to know is it ok for me to drive for another week or so with the "brake light circuit "warning on?
[snapback]267198[/snapback]​

Anybody?is it ok for me to drive for another week or so with the "brake light circuit "warning on?
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[/b][/quote]

Have someone check your lights (visually) I have been driving with that light burning for about a year. Hoping it will burn out soon :lol:
 
#9 ·
Yes it's driveable. Your car won't explode, just back the car against a wall or something and tap the brakes, if you see red lights, you will be OK. Get it fixed soon since cops don't like it when people's headlights or taillights do not work.

I drove around like this for 6 months intermittently without a problem or anyone saying my lights were out. Sometimes one taillight wouldn't work, sometimes it did. Sometimes the other wouldn't work, sometimes it did.
 
#10 ·
I have the same warning have had it since I bought the car 4 months ago. As soon as I got the car I had the 75k tune up done and they said that it was a sensor. They told me I could replace it for $80, or live with it warning me, but that nothing was actually wrong. I also have a "check coolant level sensor" that is out and same deal with it. I did neither. It also doesn't come on every time I start the car just sometimes. It gives me one error one time and something else the next time. It is completely random for me.

Don't know if that helps at all, I would get it checked out if you are real worried about it.
 
#11 ·
#12 ·
i had and still have this problem. i took it to a dealer and they told me it was an ABS Sensor unit and that it would be around $800 to replace. as u might have guessed i passed up the offer. ive been driving around with the warning coming on and off for a few months but still no cops
 
#13 ·
First of all the abs system, when there are faults displays a light on the dashboard where the speed and rev is..
on the obc = on board computer, the one on the center console, the brake warning light problem is caused by some reasons, first check to see all the lights are working, and even if they are make sure the contacts are clean, using a good contact cleaner helps. then there is the brake light swicth on top of your brake pedal, there was a recal on this. the swcth works, but because o defect on production, the swich has a higher internal resistance, therefore trigging the message.
the way this sistem works is by monitoring that there is a closed look on the light circuit, if there is a light that if burn out, then the loop is broken and so it triggers the computer. the way it monitors the loop is by resistance on the wires, if there is too much resistance build up it will trigger the computer.

so with time, moisture creates rust wich in turn creates electrical resistance on cundoctors. then the brake swicht when working also creates big resistance and it makes the obc mad.

Rule to fix this. first check the light bulbs, the light holders and use contact cleaner to clean all metal contacts on the tailight. also check if the light number that is on that hole macthes the factory specification. all lights have a universal model number this gurantees that you are using the specified light for that job, light bulb specification should be on the onwers manual..

if after doing this the message comes back, then replace the swicth, get it at dealer or ebay...

and the worst case scenario that should only be done if the above does not work, replace the obc light monitoring box. this light monitoring box sits under the dashboard on the drivers side, us spec. its a little blck box with some 2 big wire clips and several wires on them. but then again this is very unlikely.

what i did find out on my car was that even after doing all the above the message comes back because of a simple problem, the tailights itself, they use a cheap metal as a conductor inside of them, and with time the contact between the light holder and the metal gets worn out so contact is deficient., so before replacing the computer, i would go and get the clear lens tailight to fix this. make sure you get good quality ones, as the cheap ones are not made to work on light monitoring systems and you have to adapt it. use bavauto.com they have ones that work like a charm..

hope this helps.
 
#14 ·
uhh. mine does that from time to time but my brake lights still work i had someone check so whatever. if it's not broken don't fix it. fucking electronic warnings
 
#15 ·
Originally posted by LivinFast67@Jan 21 2005, 12:51 AM
if it's not broken don't fix it. fucking electronic warnings
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Hey is the thing is complaining there is a light burn when there is not, there is something wrong././

also as i wrote above, the brake swicth had defect, and this triggers the warning quite often.. also after 10 years, the factory tailights get rusty. and with bad contacts.. so a good spray cleaner agent always help.. i had the same issue on my car.. guess what, i did exactly what i described above,, the light warning ghosts have been long gone!!

im telling you, this is the fix, just read above..
 
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