Circuit Operation

The electronically tuned Radio receives power from the RADIO Fuse and CKT 43 when the Ignition Switch is in "RUN" or "ACCY." The clock and memory circuits receive power from The Multi-Function Alarm Module's Parasitic Power Control through CKT 1733 at all times. The Radio is grounded through CKT 250. 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 8 to the Radio panel light 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 8.


NOTICE TO TECHNICIANS: Electromagnetic Interference (EMI) can cause a fewer number of stations to be received in one of the three modes. The EMI can be caused by various vehicle components. This may be the cause of the differences in reception. Check for components powered up in the three various key positions. This may eliminate Engine running components, Ignition on components, etc. For example, if the same number of stations are received with the Engine running as when the Engine was off, the components active with the Engine running are not causing the interference.