overhead indicator "brake light" - all bulbs fine, what could it be from?

[clydesdale]

There is plenty of brake fluid in the resevoir. What does this check "brake lights" light actually mean? Is their a fluid sensor that might be bad? Thanks

[Garageaholic]

No, it's not the fluid sensor (that would be in your instrument cluster). The check light for brake lights means that your brake lights aren't OEM BMW brake light bulbs. That means that it's not registering the exact same amount of resistance that let's say your autozone bulbs are putting out. Therefore, even though the bulb works, it's registering that it's not working. Think of it as a mini short. Most E30's have this problem, at least the 4 that I have owned. Wierd

[clydesdale]

Are you saying that I need to buy a bmw bulb?

[markseven]

My car does that intermittently and only when I first start her in the mornings. The light goes away after I hit the brakes for the first time.

[Garageaholic]

My car does that intermittently and only when I first start her in the mornings. The light goes away after I hit the brakes for the first time.

Me too.


I would get a BMW bulb. Ask them about the problem. Could have been a recall. You have nothing to lose.

[Jonathan M3]

My car does that intermittently and only when I first start her in the mornings. The light goes away after I hit the brakes for the first time.

Its supposed to do that. The check control system is not able to check the circuit for a short/burnt bulb until you use the brake lights.

[StereoInstaller1]

OK, so here is how the "brake check" is supposed to work: Fire up your car and it comes on. Hit the brakes once and it goes off UNLESS it sees an issue with the brake light circuit, then it stays on. If you lose a brake light bulb while driving, it will come back on, and will not shut off until the key is turned off.

Mine worked like ass from the day I got the car.

I was told it was caused by the excess resistance of the bulbs I used. I said BULLSHIT! BMW could not possibly build a circuit that tested their resistance that closely...it would be just too dumb. That sounds like urban legend (bullshit) to me.

Some parts jockey came up with that crap to impress someone into buying bulbs, trust me.

So, I started digging into the real resistance issues.

Here is what I did to FIX mine.

1. I located the actual "resistance checker" (still do not know what it is called) but it is a small white or black box located under the trunk liner above the left rear wheelwell, near the amplifier/antenna. On 3 different cars in a row, I found corrosion on the terminals where the plug is attached.

I cleaned this carefully with CRC/ Elelctronics cleaner and re-installed.

2. I took apart the taillight housings. There is a single 1/4" connector that supplies ground to ALL of the taillights (on that side), betweeen the backing plate and the plastic housing. Every single one of these has been slightly melted, loose, and corroded. I believe that this single connection has mae the difference between mine working flawlessly and the crap I put up with before.

I took that connector apart and cleaned, tightened and made sure all was clean in the main connector too.

3. Did the same "clean and tighten" technique to the brakelight housing too.

Keep in mind you absolutely MUST remove the metal backing plate from each taillight housing covers (yes, the gray part) to see the connector I am referring to in step 2. If you look at the little "Dzus" style fastener (AKA the "quarter turn thingie") that, in conjunction with the small plastic tabs are what mounts the metal plate to the plastic housing. It is the primary connection between the metal plate and the housing that fails.

In my cars' case, the taillight gaskets were so shot that leakage was rampant, filling the trunk with water. New gaskets fixed all of the leaks. I recommend it highly!

Every since I did the thourough cleaning, my DIC has had flawless performance...just like God and BMW expected.

Luke

[E30 Cabrio]

I've used aftermarket bulbs without any problems.

If the light is staying on, check to see if your brake lights are working.

If none of them come on, your brake light switch at the brake pedal needs adjustment or replacement.

If all your brake lights work, but the check panel light stays on, the most likely culprit is a little PC board that controls the 3rd brake light.

It's located in the 3rd brake light housing and you can either replace it or bypass it.

I bypassed mine, but keep in mind if you do that and your 3rd brake light goes out, it won't warn you on the check panel.

[Drew325is]

I cleaned this carefully with CRC/ Elelctronics cleaner and re-installed.

BMW should've made a space in the E30 tool kit for contact cleaner...it's just about one of the most important maintenance tools for an E30!...The number of problems I've fixed just by cleaning terminals is amazing.

As for the bulbs issue...I'm using aftermarket, and the only problem has seemed to have been dirty contacts on the bulbs. Once cleaned they've been fine.

[etxxz]

My car does that intermittently and only when I first start her in the mornings. The light goes away after I hit the brakes for the first time.

+1

i went to advance auto parts and got myself a pack of bulbs and it didnt do anything.

[Garageaholic]

Great writeup. Thanx luke

[JPL]

thank god. my car has been doin that since i got it. thanks luke, i thought i was going to have to live with that shit for ever.

[nando]

if your car is doing it intermittently, it's not the bulbs or anything like that. it's the brake light switch that's under your brake pedal, it's going out. it's like a $5 part from bavauto, and it takes about 2 minutes to put in.

[clydesdale]

I know how the overhead is supposed to work. But for me the light stays on even after the first time I step on the pedal. I will try what you guys suggested. Thanks

[E30 Cabrio]

If your brake lights are working but the Check Panel brake light doesn't go out, it's going to be the PC board for your 3rd brake light.

Just go ahead and bypass it, or replace it, but that will require soldering.