One problem related to brake antilock control unit/module has been reported for the 1998 Kia Motor Sportage. The most recently reported issues are listed below.
The brake light first came on and went off for a day or two and then came on steady. Took to dealer and they replaced the abs brake mode solenoid sensor. After 1 week brake light came back on, and then master cylinder went. After 2 weeks brake light came back on for less than a second and went back off. Then last week light came back on for another second and wnet back out. I haven't taken it back to dealer yet.