Well other than checking the connection at the wheels, you can remove them and clean them off, since they are magnetic, metal shavings do cling to them. just wipe them all off and reinstall them and see if the light still comes on.
CJ 2x. Im a broken record, but I bet half the electrical problems are he are bad. dirty/corroded connections. You can often just jiggle the connectors, slide them on and of a few times and you've got a conection.