Circuit Operation

The Radio receives battery voltage at all times on CKT 640 through the RADIO Fuse in the UH Electrical Center to keep the clock and preset station memory alive when the Ignition is OFF. With the Ignition Switch in ACCY or RUN, voltage is applied to CKT 43 through the RADIO Fuse in the Fuse Block to enable Radio operation. The Radio is grounded through CKT 351. When the Ignition is in RUN or ACCY, the vacuum fluorescent display illuminates to display the time or Radio frequency setting.

The Radio illumination is controlled by the Instrument Panel Lamp Dimmer. When the Headlamp 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 Switch is switched to PARK or HEAD, voltage is applied through CKT 308 to the Radio, signaling the internal circuitry to adjust the brightness of the vacuum fluorescent display to a level determined by the voltage of CKT 230.

Compact Disc And Cassette Player
If equipped, the Compact Disc or Cassette Player is part of the Radio Unit. When operating, the same power required by the Radio is necessary for Tape or Disc Player operation.

Amplifier
The Low Frequency Audio Amplifier is controlled by the Radio. When the Radio is turned on, battery voltage from the Radio is applied to the Low Frequency Audio Amplifier, enabling the Low Frequency Audio Amplifier and turning on the Front Door Speakers. When the Radio is turned off, battery voltage is removed from the Low Frequency Audio Amplifier, turning it off.