GM Service Manual Online
For 1990-2009 cars only

Radio

Voltage is available at all times to the radio from RADIO-B fuse 19 through CKT 1140 (ORN). This voltage provides power to the radio memory storage for time and station presets. The voltage also provides power to the time and to the theftlock circuit, if provided. Operating power is available to the radio when the ignition switch is in RUN or ACCY from RADIO-I fuse 17 through CKT 43 (YEL). The radio is grounded by CKT 150 at ground G201. Refer to Radio Controls for a description of radio controls and functions.

CKT 314 (PNK) controls the optional power antenna. Voltage on this wire raises the power antenna automatically. When the radio is turned off, the voltage is removed, and the antenna lowers. Refer to Power Antenna Schematics .

CKT  817 (DK GRN) provides the optional speed compensating volume signal from the vehicle control module (gasoline engines) or from the vehicle speed sensor buffer (diesel engines). This signal switches to grounds at a frequency of 4000 pulses per mile. With the use of the adjustments on the radio, you may increase the volume in proportion to vehicle speed in order to compensate for road and wind noise. When the vehicle stops, the radio volume returns to the previously adjusted volume.

Remote Compact Disc Player (Optional)

The radio supplies voltage to the compact disc player with the ignition switch in RUN and the radio control head ON.

If the remote compact player is in PLAY, the compact disc player returns an ON signal and the stereo audio signals to the radio. The ON signal causes the receiver circuitry to ignore the signals from the tuner and to send the audio signals from the compact disc player to the speakers. If you push the EJECT button in the compact disc player, the ON signal terminates and the radio returns to normal operation.