One problem related to brake antilock control unit/module has been reported for the 1998 GMC Sierra. The most recently reported issues are listed below.
Contact states: the anti-lock brake sensor activates when driving on dry road at low to normal speed, 20-40 mph. The anti-lock brake sensor activates when it is not supposed to or when it is not an emergency. The car was taken to the dealer. However, they did not see that as the problem, and the anti-lock brakes were not repaired. The anti-lock brake sensor activates often. Complaint to dealer have been ignored. This happened since she bought the car. The number failures it is over 500. The date of incident date was when the problem started to occur. The brakes were replaced, for the fifth time, the but the abs sensor was not checked.