My abs light comes on, the windshield whipers come on, the head lights go off, my ac quits working,and the brake light comes on...
ABS LIGHTS on 1998 Volkswagen Cabrio
For the ABS brake light I would do a quick visual check for damage to any of the electrical harnesses at the wheels for damage caused by road debris. VW have had problems with the brake light switch going bad and the control module for the ABS system giving problems. You have so many electrical problems I would look for a good independent VW specialty shop experienced in tracing down electrical problems with VW. Make calls and see who you feel seems confident and experienced in tracing electrical problems in VW's.
I had the same issue with the same vehicle it was a electric problem www.nationalmobilemechanics.com got me fixed up in an hour.
you have a faulty ignition switch, not the cylinder where the key goes but the electrical part of the ignition ie; the switch.