break light circuit code? won’t go away!!!

[Lev36]

i’m getting this break light circuit code

second picture is me holding breaks. everything seems normal to me.

[jclausen]

Replace the brake light switch and it will go away

[Bela27]

I had the same problem, 99% it's the brake light switch...

[ChuckDizzle]

It's a very common problem with e36s. The brake switch is the culprit 99.9% of the time.

[blckstrm]

i’m getting this break light circuit code
second picture is me holding breaks. everything seems normal to me.

^ What these guys said.

Also, you need to get it out and see if you have the 2 or the 4 pin version. I order the wrong version every time, and then I just take it apart, clean it, and put it back in. I've done this twice in the last 70k miles. The contacts just get oxidized. It's not hard to actually fix vs replace, but if you break off one of the tabs trying to get it out you'll have to get a new one.

[gc325is]

The 4 pin Brake light switch is under the pedal.

Most of the time you will need to break it apart to remove. I taped it up to check the operation.
The ears around the red plunger are hard to release while upside down in the car.

A new one is priced @ $20 - $40 OEM to BMW
If you get it out in one piece you can clean the contacts but the contact tension and alignment may be off too.

[MParallel]

Wow another new topic for this 20 year old problem. It was highly due.

Yes, but my lights are just fine. While OBC doesn’t even mention anything about lights.

Nobody ffing reads an owner’s manual anymore.

[shogun]

It's a very common problem with e36s. The brake switch is the culprit 99.9% of the time.

Not only E36, 61318360417 STOP LIGHT SWITCH 4-POLIG/MECH. From: 03/01/1994 To:- ,Supersedes: 61311382385 (03/01/1988 — 12/28/1994), Part 61318360417 was found on the following vehicles: E30, E36, E34 , E32, E31, Z3 E36

see here the fix to open and clean the switch http://www.nmia.com/~dgnrg/page_25.htm

[MParallel]

I opened up the switch before and expected some electronics, but to my surprise, all mechanical. So what could fail? Gonna try the cleaning procedure.

I thought maybe the copper contacts lost their elasticity.

[shogun]

See my website how we make it on the E32 + E34 without opening or removing the switch, http://twrite.org/shogunnew/topmenu.html it is a pdf file , left side click fixes>>>>brakes>>>Check control fault message repair
Maybe it also works on your E36.

we insert a #22 bare wire (0.025”) into Pin 7 of the Green CCM connector. It's the middle contact of the back row. Then connect a jumper wire to the sharp end of your 12V Test Probe (not a voltmeter!), with its “Ground” clamp clipped onto the battery Charging Post.
Now sit in Driver's seat and press the brake pedal 10 times. See that the test lamp lights every time the pedal is pushed.
Why does this work? Because the current from pin 7 of CCM X19 is too small to keep the contact of the Brake Light Switch clean of oxides. The extra current from the test lamp (about 0.3 Amps) cleans the contact. There is no need to replace the switch!

Includes a lot of pics

Note: the pin numbers are the ones on E34 and E32 CCM, double check the pinout on E36 CCM, on E32/E34 pin 7 on X19 is brake light test http://www.bimmerboard.com/forums/posts/275437

[MParallel]

Under “Fixes” there is no “brakes” entry listed.

[shogun]

There is, first on the left side index click fixes, then look at the main section menue index (not on left side) which opens after you clicked on the left side index. That is why I mentioned on the main page: NOTE: the sub-menus are not complete. Use the section menus!
But here in post 2 is a direct link to that DIY https://www.bimmerforums.com/forum/s...g-Light-Repair

Does somebody have the detailed pinout of the black and white plugs of the E36 CCM?
edit, here in German langage
X1070 schwarz/black http://www.vogtonline.de/misc/public...aene/x1070.jpg
X1071 weiss/white http://www.vogtonline.de/misc/public...aene/x1071.jpg

[gc325is]

Why do the switches fail? There are two circuits in the one switch, Brake pedal pressed, and brake power applied.

Note the brake light circuit have a larger contact and spring. The computer sensor side is smaller and the spring force wore down with use thus not making contact per computer sensor design and causing a fail circuit light. Interesting thing is I tried other brands and they are also made the same.

[johnf]

... we insert a #22 bare wire (0.025”) into Pin 7 of the Green CCM connector. It's the middle contact of the back row. Then connect a jumper wire to the sharp end of your 12V Test Probe.... The extra current from the test lamp (about 0.3 Amps) cleans the contact....

The E36 brake light test switch contacts are gold-plated. Such high currents are a good way to burn the plating off and cause the underlying base metal to corrode.

Writing as someone who was happy to avoid the issue when he ordered a car without check control, I thought the problem was with the other, working contacts: eroding away from the ca. 50A surges they suffer, lighting up 63W of cold brake light filaments. Didn't BMW address that issue with an alternate, solid-state brake light switch for the E32 and E34?

[shogun]

all use the same switches: 61318360417 STOP LIGHT SWITCH 4-POLIG/MECH. From: 03/01/1994 To:- ,Supersedes: 61311382385 (03/01/1988 — 12/28/1994), Part 61318360417 was found on the following vehicles: E30, E36, E34 , E32, E31, Z3 E36

[johnf]

The fancy alternate is p/n 61 31 8 356 527. I would buy one, just for giggles, but is a bit pricey and I have already addressed the issue on my car.

[MParallel]

The fancy alternate is p/n 61 31 8 356 527. I would buy one, just for giggles, but is a bit pricey and I have already addressed the issue on my car.

Intersting. Is that a solid state version? Or what makes it fancy.

If anything, I’d expect e32/e34 to use older electrics.

So running lots of current through them is not the solution. Still, it would need serious corrotion to not make good contact, unless the CC module checks for more than just a complete circuit.

[johnf]

Intersting. Is that a solid state version?....

That is what I would expect, given the heat sink and electronic parts. It may have been an interim solution until BMW could sufficiently refine its less costly, mechanical brake light switches.

So running lots of current through them is not the solution....

Gold plated contacts are typically good to about 0.4VA, or roughly 30mA@12V.

Still, it would need serious corrosion to not make good contact.

I am not sure what is going on. If someone were to send me a misbehaving switch, I would be happy to look at it under a microscope.

Unless the CC module checks for more than just a complete circuit.

The MID checks the brake-light-related signals from the check control module, and the high current brake light switch contacts, once it sees the low current, test contacts close. Each brake light gets its power through a resistive shunt which produces a small voltage drop the check control module senses. IIRC, if a lamp sensing IC, inside the CC module, sees less than a 7-20mV drop, it outputs a brake light fault. I wonder if the issue could be the test switch contacts closing too soon because of the working contacts being worn so far down.

[MParallel]

The fancy alternate is p/n 61 31 8 356 527. I would buy one, just for giggles, but is a bit pricey and I have already addressed the issue on my car.

Just looked it up. Wow I’m genuinely surprised. Never ever seen this part before. It clearly shows a pcb so it might be solid state. They are also pretty expensive, but so is the original E36 one. And if this fixes this for good...

Do wonder if its operation is the same and also works with the E36 Check Control module. I don’t know if these differ in how they work. The E36 is only hot monitoring lights afaik.

I found an old 1992 brake light switch and opened it up. It’s more complicated than the current mechanical switch, with 4 timy springs and rocker levers. There is a clear delay between disconnecting the first contact and the second one.

Much less noticeable on the current one.

[gc325is]

Answer to ... I found an old 1992 brake light switch and opened it up. It’s more complicated than the current mechanical switch, with 4 tiny springs and rocker levers. There is a clear delay between disconnecting the first contact and the second one.

Untitled.jpg

The computer contact on top is Closed AFTER the Brake light circuit is Closed Thus the computer knows the brake light is activated and should draw current. (Updated ... because I forgot the switch is normally depressed open position and is closed when the pedal is pressed) The question now is ... if both fail as in a connector removal.. will the computer show a error?

[MParallel]

If the computer contact is closed before the brake light circuit, how does the computer know the brake light is activated?

[johnf]

Yes, it has to be the other way around. From the BMW NA 1992 ETM supplement, page 6581.2A-5 (On-Board Computer V):

The on-board computer (BC) itself must evaluate several inputs [not outputs!] of the check module. These are:

• brake light switch, for fuse monitoring
• brake light test switch (active after the brake light switch).

[johnf]

... if both [switches] fail as in a connector removal.. will the computer show a error?

Perhaps more usefully, the check control display or OBC will not know if the brake lights should be lit, if you were to to disconnect the test switch contact – which you could conveniently do by sliding the corresponding contact out of the connector at the back of the display.

[gc325is]

johnf.... MParallel

You are correct... (forgot the switch is normally pressed in in the open position and closed when the pedal is pressed and the plunger extends out) Thus light on before computer contact is on.

The on-board computer (BC) itself must evaluate several inputs [not outputs!] of the check module. These are:

• brake light switch, for fuse monitoring
• brake light test switch (active after the brake light switch).

Brake light failure...
Based on the information on people who swap LED bulbs in for brake light.. The computer has a current sense line for when all the lights are activated. less current and the Brake light failure will illuminate. LED bulb owners thus had to put in a resistor to draw more current.

I was able to replace one set of tail light bulb to LED without causing an error and I replaced the 3rd high mount brake light to LED. *** We all know the 3rd mount light often fails due to overheating ***