ABS Light Always ON

[Diseasel300]

This pertains to a 1983 500SL Euro (don't shoot me) that was never "Federalized", so there could be some differences between this car and the normal North American models.

Finally tossed a master cylinder in the SL and dragged it out of storage. As part of the TLC fest, I pulled the instrument cluster and painted the pointers on the various gauges.

Long story short, the bulb holder for the ABS light was empty. I got a new bulb and put it in and now when I start the car it comes on with the rest of the idiot lights prior to start, but then never goes off. I assume this is why the bulb was missing. I can confirm that the ABS does NOT work, can easily lock up the brakes and has been that way since we got the car back in the 90s.

I'd really like to get this taken care of. The car is scary enough as it is (seriously too much power for the chassis), and locking up the brakes causes my pants distress. I just don't know where to start with this. All the fuses are good and the OVP relay is working fine. Everything else in the car is working like it should, with the exception of the ABS and the A/C.

Where to start looking? I'd be ahead already, but can't seem to find my copy of the FSM for this car, annoyingly