Red Brake Dash Light stays on - '86 420SEL
 

The red dash brake light is on continuously. Unplugged the sensor at the fluid resevoir and it goes out. While unplugged, tried setting and releasing the parking brake and it goes on and off properly. Brake pads are OK. Any suggestions?

Thanks.

either the brake fluid is low, or the sensor in the reservoir is defective

Have you verified the proper brake fluid level in both the front and rear reservoirs? If so, the level switch in the reservoir may be bad.

Sorry, first post got eaten and forgot to add that the fluid level was fine in the second post.

Can you just unplug the sensor or is there a way to bring it back to life?

Funny thing, the alarm started waking the neighbours the other night so I had to unplug it as well.....

I don't know if you can replace just the sensor, or if you need to replace the entire reservoir:

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ41M10V00Q1&year=1986&make=MB&model=420-SEL-001&category=N&part=Brake+Reservoir

Follow up
 

It turns out there was a leak in the right rear caliper. It's been replaced and everything seems to be OK so far.

Thanks for the help.