Glad you fixed your vacuum leak through one of my posts. Now to locate your OVP. You'll find it just inboard of the brake master cylinder, mounted on the firewall. The body will be silver with a red top, should also have a clear plastic flip top cover. Under the flip top you should have one, or two fuses depending on whether you have a newer OVP or not (newer has two). The fuse(s) is a 10amp blade type, not the ceramic type. Check the fuse first, replace if blown and see if that shuts down the ABS light.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.