Phantom Brake Light on Check Panel

[E30 Cabrio]

Lately, my Brake Light on the Check Panel has been coming on.
It goes out when I first start the car and step on the Brake pedal, but after a short time driving, it will come back on.

I replaced both bulbs in the tails with bulbs from the stealership, and I verified that all 3 brake lights come on, even with the Check Panel Brake Light lit up.

When I bought the car last year, The Brake Light was constantly on, and I traced it to a bad circuit board in the 3rd brake light so I bypassed the tiny 1" x 1.5" or so circuit board in the 3rd brake light by cutting and resoldering the wires.

The only purpose that PC board serves is to notify the driver via the Check Panel if the 3rd brake light goes out, so removing the PC board shouldn't have any affect, and this was done nearly a year ago.

I will also check/replace the plunger switch under the brake pedal, but I don't think it's related to that as the Brake Light on the Check Panel will come on kind of randomly.

I also checked the brake light housings and verified that they are properly connected and no corrosion. The car only has 113K on it and is clean and rust free.

I also have a spare Check Panel I can try, just to eliminate that from the mix.

Other than what I've done and what I plan to do, any other thoughts?

Thanks as always.

[JamesE30]

my brake warning light comes on occasionally when i turn the car on,
As soon as i touch the brake it goes out,
My brake lights are perfect and do not malfunction,
When i had it serviced the guys just said it needed "further investigation" but that it wasnt worth the money to fix...

So ill just live with it, Its pretty common so i wouldn't worry.

Also they deemed the "inspection" light as needing "further investigation"
It doesn't go off, they are quite inaccurate and the tech guys just recommended pulling the globe if i ever take the cluster out...
Apparently thats really common too..


Hope that helps.

[MA325is88]

Replace your "check relay". located in the trunk. I have one for sale if you need it.

[KangamangusDriver]

If resistance is too high, either due to corrosion or incorrect bulbs
in some cases will cause the check panel/light to come on.

Make sure all connections are clean and proper bulbs are in proper locations

[threlevenguy]

i have the same problem but when i press the brake the light turns off..as far as the inspection light goes a bmw tech at work told me that the small batteries behind the cluster are probably bad and would need replacement

[markseven]

Tech Talk in the latest Roundel covers this. Make sure all of your tail bulbs have stainless steel bases not bronze.

[Jscotty]

Also make sure that the panels that hold the bulbs are screwed in tightly and you do not have anything rolling around in your trunk that could bump up against them. I carry a lot of hand tools in my trunk and sometimes when one of the heavy cases hits the inside of the tail light assembly I will get the brake light warning or a tail light warning. Also you might want to clean the contacts on the assembly so to ensure that you are getting a good connection.

[E30 Cabrio]

The bulbs are Stainless and came from the dealership.

The Brake Light goes out when I first start the car and step on the brake pedal, but will soon come on afterwards. Sometimes. Even though all 3 Brake lights are functioning as far as I know as I checked them yesterday by backing up to the glass doors at work and checking the reflection of the lights functioning, and this was with the Check Panel/Brake Light on.

The Panels that hold the bulbs are good and screwed in correctly and connected tight with no corrosion.

I'll check my Bentley Manual when I get home, but for now, does anyone know where the brake relay resides in the trunk of Cabrios, and can I check it with a Multimeter?

Thanks.

BTW, I did carry a 40" x 36" satellite dish in the trunk last week that barely fit, and the problem seemed to start shortly after that, so I'm thinking I might have banged the brake relay loose or something similar.

[BeirBrennerE30]

FYI to everyone that thinks this is a problem... When you first start your car the brakelight light on the check panel is supposed to turn on. It will then go out when you hit the brakes for the first time.

[nando]

your brake light switch is going out. it has nothing to do with your bulbs. it's a $5 part, above the brake pedal. takes about 10 minutes to replace.

[E30 Cabrio]

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, so I don't think that would have anything to do with the Stop Light Switch under the Brake Pedal, nor is the issue the brake light coming on when I first start the car as that is normal behavior.

I will check and replace the stop switch under the brake pedal, but the cost is closer to $30.00 than $10.00 for 88 and up E30's.

I also know the symptoms of a stop switch under the brake pedal being faulty as that happened on my old 86 ES, and this is behaving much differently.

Seems some people are commenting without reading and/or understanding the original post.

Also, as stated in the original post, I bought new bulbs at the dealership, so they are not brass, but Stainless and I also ensured that the light holders were secured correctly and that the connectors are properly connected and free of corrosion.

Any other suggestions would be appreciated, but replying without reading the post describing the problem isn't doing anyone any good.

Sorry if I sound like an ingrate, but when people post responses without understanding or reading the issue, it is somewhat annoying.

Again, I appreciate the help, but people replying without reading the original post is a pet peeve of mine.

I know you guys have good intentions, but I've already investigated many of the things that people are suggesting I do, as previously stated.

Thanks again.

[Dave]

I would try what nando suggests - and the stop light switch ran me about $6 last time I bought one online.

And yes, I read all of your post(s).

:-)

EDIT: the Brake light switch is $5.83 at fap99.com, the place I bought the spare one I keep in my track box.

[gazellebeigem3]

Im having the same problem in my 71 f100, im eager for the outcome!

[Mossman]

I have the same problem but it's cuz I did a hack job of wiring the 3rd brake light. It works but I guess resistance is higher than spec allows so after like 5 seconds of holding down the brakes I get the check brake light. When I have someone hold the 3rd brake light connector tighter it doesn't go on, but I can't make it any better without buying a whole new 3rd brake light assembly and I'm too cheap.

Anyhow since yours is a vert too I bet it has something to do with it

[StereoInstaller1]

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