I just bought a used 99 Passat GLS 1.8T and seem to have the same problem as other forum users.
My problem is intermittent, but still very annoying. I have been trying to find a solution and came across another forum (see below)
I hope this helps in any way.
Web address is
http://forums.vwvortex.com/zerothread?id=1421315
Here is a small part of discussion:
A '95 Passat I am servicing has the ABS light coming on also. Doing a scan-code check revealed one of the pump's coils (or some pump part) was reading a bad value or something like that. I can get you the specific error code if you're interested in comparing... Anyway, based on that fault code, it appears a new ABS pump would be required. Since that is so much $$$ to buy the part and replace it, we are just putting up with the ABS light coming on.
Here is what the dealership scan ($50) came up with on our '95 Passat VR6 ABS light problem:
"03 brake electronics
1H0907379E
ABS/EDS TEVES 04
2 Fault detected
00259 035
Right Front ABS Inlet Valve -N99-
00532 035
Supply voltage"
(there were several other fault codes that came on due to a loose/intermittent battery cable battery connection, so ignore the "supply voltage" codes.)
Troubleshooting the "Right front ABS Inlet Valve
Jake Russell
1981 VW Rabbit "GTD" autocrosser - SCCA FSP class