One problem related to brake sensor has been reported for the 1999 GMC Safari. The most recently reported issues are listed below.
About a year ago the problem began. When braking at low speeds about 5-10 mph abs kicks in and a grinding sound occurs. This causes extended stopping distances. All wheel drive, all wheel antilock to the owner's knowledge. No warning lights illuminated and the dealer said that the abs sensor looked corroded. The vehicle was put on the diagnostic machine but it showed no codes. When the abs fuse is pulled the car works fine but has no abs. The owner hasn't disconnected the abs fuse. The vehicle has not been repaired yet and the problem has remained about the same. The problem occurs about 90 percent of the time during low speed brake applications.