I'm a little confused about just what your problem is. The light to which you are referring is the little orange light in the switch and not the ABS light in the instrument cluster, right?

There's nothing I can think of that would directly link a failure of the light in the TRACS switch to an odometer gear replacement. Perhaps the dashboard got bumped just right to break the filament in the bulb.

If you can, check the operation of the TRACS system. Note that the TRACS switch only turns on/off the traction control feature, not the ABS which is always on. Even easier, swap switch bulbs with the one in the rear defrost, seat heater, or fog light switch. The bulbs come out of the back of the switch with a quarter-turn of the white round bulb holder (a little flat-head screwdriver works well here).

-Will
--
850 / Mini