Phantom Brake Light on Check Panel

[E30 Cabrio]

I've had a Stop Switch fail on me before, and this is completely different behavior, as the "Brake Check" light on the Check panel will randomly come on, even when not braking, and all 3 brake lights work.

I'll say it again, and only once more. it's the brake light switch...

[StereoInstaller1]

I'll say it again, and only once more. it's the brake light switch...

Go ahead and say it again, you will still be WRONG.

Luke

[E30 Cabrio]

So yesterday I took apart the 3rd brake light, and the connectors had some corrosion, but nothing major.

I cleaned them up with a little sandpaper and electrical cleaner, and reconnected them.

Haven't seen the problem come back, but time will tell.

The corrosion didn't look that bad, so I'm still leaning towards a bad check relay, which I can't seem to find it on the cabrio.

I'll keep the post updated.

[StereoInstaller1]

So yesterday I took apart the 3rd brake light, and the connectors had some corrosion, but nothing major.

I cleaned them up with a little sandpaper and electrical cleaner, and reconnected them.

Haven't seen the problem come back, but time will tell.

The corrosion didn't look that bad, so I'm still leaning towards a bad check relay, which I can't seem to find it on the cabrio.

I'll keep the post updated.

The ever-so-helpful Mr. Lee (of the serious stopping Massive Brakes) posted a link to TONS of BMW electrical service manuals: http://wedophones.com/BMWManualsLead.htm.

I have downloaded all of the ones useful to me...so I got them while they last.

Luke

[mark1]

Thanks StereoInstaller1, Fabulous resource. The rear check relay is located near left rear window motor in cabs. Of course the lid light has its own relay in the housing. I will try jumping that out tonight to see if I can get the light to go out.

[E30 Cabrio]

Thanks StereoInstaller1, Fabulous resource. The rear check relay is located near left rear window motor in cabs. Of course the lid light has its own relay in the housing. I will try jumping that out tonight to see if I can get the light to go out.

When I first bought my Cabby last year, the Brake Light on the check panel wouldn't go out, despite the fact that all 3 lights worked.

I bypassed the relay/PC board in the 3rd brake light, which resolved the issue.

Recently, the Brake Check light has returned intermittently, but at least daily, then I took apart the 3rd brake light, cleaned the contacts a week ago, and no problems since.

[87Blue325iC]

Bypassed the 3rd brake light circuit board in my cabby yesterday: Cut the circuit board out, spliced the green/black wires together, connected the brown wire directly to the light... and now no stupid "always on" check brake light!!! It goes off when you tap the brakes (as it is supposed to). Makes me very happy.

[DaveSmed]

Again, the brake light switch does go out when I first step on the pedal when starting the car up initially. The problem is that soon afterwards, just idling in the driveway with my foot off of the brake pedal, the brake light will come back on......

Hmm. Thats the kicker right there. ^^

I'll say it again, and only once more. it's the brake light switch...

Well, assuming he's not posting just to see his name in the thread, maybe he had a similar issue fixed by changing it?

How about the possibility of corrosion in the brake pedal switch leaking enough voltage to trip the check control but not illuminate the lights when at rest.

Figure for that light to trip without his foot on the brake, voltage has to be leaking from somewhere. The 20 year old switch is as good as any place to start, esp. considering were talking about a cab which is almost guaranteed to have had an interior leak at some point in its life.

[e34 530]

James, you can fix your "INSPECTION" light for free, using a short chunk of wire.

Read this: http://www.unofficialbmw.com/repair_faqs/sil.html

Luke

Can you use a paperclip to ground the 2 pins?

[bimmer8604]

my brake check light comes on when i hit my right turn signal. im fucked.

[kennyvb]

Guys, I am gonna speak on this. Trust me, I truly know my shit.

OK first:

THE STAINLESS BASE BULB THEORY IS BULLSHIT!

Any normal bulb is just fine. This circuit is just not that sensitive. Use those WalMart bulbs all you want, they are the same electrically.

The "bad brake switch" theory is wrong too. The circuit sees a bad switch as simply not using the brakes...absolutely no bearing on the DIC LED being on or not. Simple logic should tell you that, but old bullshit internet rumours die hard.

The real issue is simply oxidization, 100% fucking guaranteed. Do EXACTLY as I say and all will be fine...total cost of about $6. Maybe an hours work.

How to fix your issue:
1. Buy a can of CRC "Electronic Circuit Cleaner", should be about $6
2. Remove both the taillight assemblies from your car
3. Find the ground point of the panel, where a cheesy little wire connects all of the bulbs to ground....TAKE IT OFF and clean it with the CRC. Use a pencil eraser if it is really bad, but get that fucker clean!
4. Remove the left trunk liner. In front of the antenna, find the 2 screws that attach the diode board that controls the taillights (NOTE: Not the amplifier, OK?) remove it and clean the contacts of the board (AFTER unplugging it!) with more CRC.
5. CLean ALL of the plugs (more CRC...see a pattern?) that attach all wiring...meaning, the the third brakelight, both taillight housings AND the diode board.
6. Reassemble, making certain to properly seat ALL plugs. Don't forget to reattach that diode board! The better you clean those connections, the more likely your problem will not come back for another 20 years.

Now, when you start the car, the "CHECK" on the instrument cluster should come on, as should the "BRAKE" indicator on the DIC. Tap the brakes, both will shut off...unless you have a bad bulb.

And JamesE30, fire your asshat mechanic. You have a retard on your hands.

Luke

Thanks, this fixed my problem.

[5Toes]

lol reminds me of when I took my car up a bumpy mountain road, coming down the check panel light for my brakes came on... verified they were fine and it eventually stopped