Circuit Operation

Important:
^ For DELCO-LOC II Anti-Theft feature or for Radio Features and Controls Operations, refer to Accessories and Optional Equipment.
^ For THEFTLOCK Anti-theft Feature or for Radio Features and Controls Operation, refer to Accessories and Optional Equipment. Accessories and Optional Equipment

The Radio receives battery voltage at all times on CKT 640 from Power Accessory Fuse 7 to keep clock and preset station memory enabled when the Ignition is "OFF". With the Ignition Switch in "ACCY," "RUN" or "RETAINED ACCESSORY POWER (RAP)," voltage is applied to CKT 43 from RADIO Fuse 17 to enable Radio operation.

When the Park Lights or Headlights are turned "ON," voltage is applied to the Radio on CKT 9 from the Headlight Switch. When voltage is applied to CKT 9 at the Radio, the Radio will illuminate the display. With the Headlights or Park Lights "ON," the Radio display may be dimmed manually using the I/P Dimmer Switch. The I/P Dimmer Switch varies the voltage on CKT 8 to the Radio to control display dimming.

SPEAKERS: CHEVROLET UQ0, U62 OR UW6 AND PONTIAC W52, W53, W54, W55, W56, W57 Entertainment Systems
With the Base Speaker System, the audio signals are amplified within the Radio, and the output signals go directly to the speakers.

SPEAKERS: PONTIAC W59 and W73 Entertainment Systems (6 SPEAKER- CONVERTIBLE ONLY)
Similar to the Base Speaker System, the audio signals are amplified within the Radio, and the output signals go directly to the 6 speakers.

SPEAKERS: CHEVROLET UZ7 (6 SPEAKER SOUND SYSTEM)
All Radio audio output signals are connected directly to the Amplifier. All of the 6 speakers in the system are connected to the Amplifier outputs, and are driven by the amplified Radio audio signals. The Amplifier is used to drive two front speaker assemblies consisting of one tweeter and one midrange speaker, two rear extended range speakers, and two rear subwoofers.

SPEAKERS: PONTIAC W54 and W55 Entertainment Systems (10 SPEAKER SOUND SYSTEM)
Radio audio output signals for two front and two rear tweeters are amplified within the Radio and the output signals go directly to the speakers.

All Radio audio output signals are also connected to the amplifier. The other six speakers in the system are connected to the Amplifier outputs, and are driven by the amplified Radio audio signals. The Amplifier is used to drive front midrange, two rear midrange, and two rear subwoofers with dual voice coils