GM Service Manual Online
For 1990-2009 cars only

The power antenna operates automatically with the operation of the radio. If you turn ON the radio, the radio places a RADIO SIGNAL ON voltage on CKT 314 (PNK). When you apply this voltage at the power antenna assembly, the power assembly motor operates in order to raise the antenna. The RADIO-B fuse 19 in the IP fuse block supplies power at all times to the power antenna through CKT 1140 (ORN). The power antenna assembly grounds through CKT 150 (BLK) to ground G201. Turning the radio OFF removes the RADIO SIGNAL ON voltage from CKT 314 (PNK) and the power antenna assembly automatically lowers the antenna. If you turn the ignition switch OFF with the radio still ON, the antenna automatically lowers. The antenna raises again when you place the ignition switch in RUN and the radio starts playing.