At each wheel, you'll (your mech) see a sensor cable disappearing into the brake ass'y.
the small hub fitting where it enters can be tapped on (hit small open end wrench w/hammer) to drive the sensor into it's wheel (that resets clearance).
This method is in the land rover service manual. Any good mechanic should understand this concept.
Upon driving, the reluctor ring in the wheel will push the sensor back to proper clearance.
This may/may not be the reason for your ABS light, but it's very common.
(My light's been on for over 4yrs. but brakes work great) - That doesn't mean your's are OK. tho'
****, I just read above, sorry. I'm not going to waste all this fingerpecking tho'
LOL
luck,greg