Brake light curcuit failure 1995 E36 325i stick

After about an hour of driving and then when I pull up, the brake curcuit failure light comes up on the OBC and the check engine light starts blinking then goes to full light. I've switched off the engine and tried to check the error code with the Peake tool but nothing, as the check engine light won't come on again and the tool reads "--". So I replaced the 4-pin brake light switch and same thing happened. I replaced the OBC (very cheap from junk yard) with the same year vehicle and no difference. The curcuit failure light still comes on and the brake lights do work, at least temporarily until the failure light comes up.
I checked the Bentley manual but no clue. The check engine light has me baffled. I thought that was usually related to emission equipment failure. I'm reluctant to take it to a mechanic as I know he'll say to replace the brake light switch, but how many times do I have to do that? I don't know why this would be time dependant and why the check engine light comes on? any help would be appreciated. As a last ditch effort, I've got another switch so I could try that, but it doesn't seem logical.

That blinking light is the check light

the check light is for the obc when it needs to tell you something and thats when you look at the screen then it tells you what it is


The check engine light literally says check engine

My car has the brake circuit error too once in a blue moon but the lights still work even with the warning

since you replaced the switch I assume you replaced it with the right one? theres a 2 and 4 pin iirc

yes, its the 4-pin switch for the OBC. the 2-pin is for the 318i with the temp clock MDI

Try another brake light switch, it's not a hard job to do. Maybe it's defective. Was the one you used new? Oem?

thanks, it's an aftermarket switch. I'll try OEM as a last resort. I still don't know why the check engine light comes on?

Is It the "check engine" or "check light"? They look similar. I recently replaced mine with an aftermarket switch and worked fine but it can be the maker of the switch or just a bad one.

"check engine light" on the dashboard flashes for a few seconds, then solid on, and comes on at the same time as the "brake curcuit failure light"on on the OBC. very strange as I can't figure out the connection between the two?

I'm pretty sure you're confusing the "Check Engine Light" with the "Check" light. They are two different things. The "Check" light (not check engine light) is supposed to come on temporarily when there is a fault somewhere in the OBC, which is what you are experiencing with the brake circuit failure.

the light right in the lower center of the instrument panel is the Check Engine Light, and that's the one that comes on with the OBC showing "Brake Curcuit Failure".
I can't figure out the connection between the two, because there shouldn't be one?

Referencing the photo below, which light turns on in your car?

^ That's wHeird....mine says "check light". ObdI?

^+1

Their inconsistency is consistent. Mine says "check control".

The key word for the OP is engine.

thanks for the photo, at least I've learnt something. now I'm not so sure which check it is? I'll have to go drive the car and wait for one of the "check" warning lights to come on, to confirm which one it is. Certainly the "check" light makes the most sense. I also took a look at the owners manual. It has a heading "check control" and the "check" button on the OBD seems like an override. The brake bulbs are working, fuses intact, new brake light switch, and I replaced the OBC.

Originally Posted by EnserioJose

^+1

Their inconsistency is consistent. Mine says "check control".

The key word for the OP is engine.

Lol I think I meant "control". I'll have to check but I don't i'll be able to since it doesn't turn on anymore.

I believe mine says check control, and I have an OBD2 car. Anyway, if the "check" light (not check engine) is turning on at the same time your OBC is warning you about the brake circuit failure, your car's system is working exactly as it is supposed to. Just fix your brake circuit and be done with this.