Brake Fluid dummy light on dash

[nealf]

of my 1990 535i now goes on when I turn the ignition OFF?? Does anyone know where to start checking for a problem?

The fluid level is fine. All that is changes is that the battery died from sittiing a couple of weeks while I was away and I jumped the car. Other than that I have not seen that light on in 9 years of ownership. Thanks.

[BillionPa]

put the battery on a trickle charger, and if its not an AGM battery, check its fluid level.

[Ross]

Also check that the float in the resevoir isn't stuck and for corrosion on the terminals.