Sounds like your exterior bulb failure monitor light wire is plugged into your ABS light on the cluster!

Had any work done behind the instrument cluster lately?

Probably worth addressing so you'll know weather your “braking when slippery” is on or off.

http://www.peachparts.com/shopforum/showthread.php?t=71691
(cluster thread)

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14