More than likely a failing sensor or corrosion from the dust shields. Most of these cars will have pretty crumbly dust shields by now unless they have been changed.
With all my 75's and Zeds it's the first thing I have looked for after plugging the car in and finding which wheel is causing the issue. The sensors are relatively cheap but will need drilling out if original.
Maybe worth just checking the connection from main loom.to sensor as well once you know which wheel.
If you don't have access to a diagnostics reader (can I mention TOAF on here
) then there is a way of checking each hub in turn with a DVM which is on here somewhere.
__________________
Jon C
Living the dream
MK IV VVTI Tiptronic TT Toyota Supra MG ZT 190+
BornTuesday, 10th July 2001 @ 09:01:10
259th ZT to run off the production line, out of 18,894
252nd ZT 190 + to be made out of 4,023
101st ZT in Solar Red (code: CEU) to be made out of 1,888