over head brake light warning

[Ceeker]

Hey peeps.

I did a complete brake service and I have no lights on. The usual overhead brake light warning light come on with ign. When I depress the brake pedal it flashes off and then back on again whether pedal is depressed or not. I checked all my rear lights and everything works. Even the 3rd brake light. I thought maybe my brake switch was gone so I replaced it with a new one and still I have it doing the same.

any ideas?

thanks

[jlevie]

The wrong bulbs or corroded sockets are the most popular cause for this. But since the light will come back on w/o pressing on the brake pedal there could be a problem in the monitor modules, wiring, or check panel.

[Ceeker]

update: cleaned nickel base bulbs and sockets. changed the warning header panel. third brake light is working fine but I'm wondering which type bulb fits this. I have a push in bulb like those 3w ones that fit into the instr cluster. seems to work fine.

still the same symptom.

I guess it's the monitor module then?

did some reading: this is the one behind the drivers side rear panel?

[jlevie]

The main module, for the tail & brake lights is behind the driver side panel in the trunk. The third brake light has it's monitor in the light housing. The third light takes the same bulb as is used in the brake lights.

The monitors consist of a a reed relay wrapped in wire. That wire is what carries the current to the bulb. If the current flow is sufficient the check panel will see the brake light switch signal and all three reed relay closures. The check panel can only "check" for a light problem when the brake switch is closed.

In this case it sounds like the check panel is warning of a bulb problem when the brake switch is open. Which in turn tends to suggest a problem with the check panel or the brake switch into to the check panel.

Using the wiring diagrams from http://wedophones.com/BMWManualsLead.htm you are going to have to do some diagnostic work to figure out what is going on.