Is it the OVP?
 

Vehicle : '86 300E

The ABS light sometimes comes on when I hit the brake pedal and stays on. If I turn the vehicle off and then on again, it sometimes comes on and sometimes not.

I am thinking that there is something loose in the OVP or a cold solder in it making intermittant contact?

Thougts?

Not likely..
OVP would light ABS all the time, not requiring pedal application.
I would suspect a WSS.

Thanks Arthur. But what is a WSS.

Wheel Speed Sensor - ABS receives input from them.