K75S '91 Brake warning light

When I use the front brake and the back brake together the warning light goes on. The same light that has always gone away once I tap the front and rear. Does not happen one at a time.

Leading up:
Burnt out the brake bulb. Easily replaced from the auto parts store.
Put in the bulb and when it didn't work I tried the fuse. Indicated on the box as Brems Schuss Licht. Cool. I assume that's Brake Stop Light auf Deutsch. Replace fuse and the brake light worked fine.

But on the way to work this morning after the above fix and I started seeing the warning light every time I use both brakes together. Very distracting.

The Pads are on the low side, but I don't think there is a pad wear warning light anyway.

Any ideas?
thanks!

Is the new brake light illuminating when both brakes are applied and the warning light is illuminated?

Yes, new brake light works independently with both front and back, but when both are applied simultaneously the warning light also goes on. It's like it goes into the initial system check. Note this just started and doesn't happen with just front or just rear.

How does that initial warning circuit work?

Another thought. Could it be the warning light relay? (no ABS by the way).

the first thing I would do is make sure the new brake bulb is the right wattage...

link to snowbums piece...

http://bmwmotorcycletech.info/K-hints.htm

j o

Resolved

Wow, the Brake Monitoring Unit (BMU) really didn't like a bulb from Napa. Well the bulb worked but it triggered a fault in the system. I just went to Greater Boston Motorsport and bought a 10W brake light bulb ($1.27) and it now functions normally. I think that's fussy but glad it's resolved.

thanks very much for the tip.

What was the wattage of the bulb from NAPA?

The replacement bulb from NAPA was only 5w, so I thought it was safe.

Why would you put a 5w bulb or even a 10w bulb in the brake light when it calls for a 21w bulb???

The taillight calls for a 10w bulb.

No wonder it didn't work properly. The bulb monitor is resistance sensitive.

There are many cars that the same thing is true for. There are some that will render the cruise control inoperative if the incorrect bulb is used, even if it is the same wattage.