GM Service Manual Online
For 1990-2009 cars only

The radio receives battery voltage from the following:

    • The RADIO ACC fuse when the ignition is in the ON or ACCY position. This circuit enables radio operation.
    • The RADIO BATTERY fuse at all times. This circuit provides the power for the clock and preset station memory.

The radio is grounded at G202 through CKT 151.

When the ignition is in the ON or ACCY position, the radio display illuminates to display the time and radio frequency setting. Turning the park lights or the headlights on, applies voltage on the park lamp circuit from the headlamp switch to the radio. Anytime the radio receives a lights-on input from the headlamp switch, the radio display illuminates. The radio display may be dimmed manually using the IP dimmer switch. The IP dimmer switch varies the voltage on the dim display circuit from the radio in order to control display dimming.

Remote Cassette Tape Player (If Equipped)

Voltage is supplied to the cassette player through the radio under the following conditions:

    • The ignition is in the ON or ACCY position.
    • The radio power switch is in the ON position.

When the remote cassette player is in the PLAY position, the cassette player returns a tape ON signal and the stereo audio signals to the radio. The tape ON signal causes the following actions to occur:

    • The receiver circuitry ignores the signals from the tuner.
    • The receiver circuitry sends the audio signals from the cassette player to the speakers.

The cassette player applies a mute signal to the radio in order prevent the audio sound of the following functions from being heard:

    • FWD
    • REV
    • SEEK

When the EJECT button is pushed on the cassette player, the following actions occur:

    • The tape ON signal terminates.
    • The radio returns to normal operation.