Mercedes Benz repair: 1987 560sel, brake light

Question
Hello my anti-Lock brake light is on and will not go off.  Does this mean that I am about to lose the system?  Also I noticed that my engine is idling high.  Do you have any ideas?

Answer
ABS light on = ABS no function.
When a fault is detected the system sets fail code and turns off all ABS function.
A soft ABS code will clear when key is off and reset with motion/brake action.
A hard code will lock out ABS and set ABS light at engine start.

Engine idle issue would require hands on diagnostic.