For 1990-2009 cars

The radio receives battery voltage at all times on CKT 640 through the RADIO fuse in the underhood electrical center. The battery voltage keeps the clock and the preset station memory alive when the ignition is off. The radio is grounded through CKT 351. When the ignition is in RUN or ACCY, the Class II data communications CKT 1044 becomes active and communicates an ignition on status to the radio to illuminate the vacuum florescent display, and allow radio operation. Vehicle speed is also communicated to the radio for the purpose of speed compensated volume.

The instrument panel lamp dimmer controls the radio illumination. When the headlamp and the instrument panel lamp dimmer switch is in PARK or HEAD, voltage is applied through the dimmer control and CKT 230 to the radio panel lamp and the internal circuitry. When the headlamp and the instrument panel lamp dimmer switch are switched to PARK or HEAD, voltage is applied through CKT 308 to the radio. The circuit signals the internal circuitry in order to adjust the brightness of the vacuum florescent display to a level determined by the voltage of CKT 230.

### CD Player and Cassette Player

If equipped, the CD player or the cassette player is part of the radio unit. When operating, the same power required by the radio is necessary for the tape or the CD player operation.