Radio/Stereo: Description and Operation

INTRODUCTION
For operation of the factory installed standard and optional radios with cassette or compact disc player, refer to the Sound Systems Operating Instructions in the Owners Manual supplied with the vehicle.

The vehicles are shipped with fuse 5 removed from the Junction Block. The fuse replaces the ignition-off draw (IOD) connector. Fuse 5 is a ten amp fuse. When removed it prevents the battery from discharging during storage.

SYSTEM OPERATION
Interference Elimination
Some components used on the vehicles are equipped with a capacitor to suppress radio frequency interference/static.

Capacitors are mounted in various locations internal to the generator, instrument cluster and windshield wiper motor.

A ground strap is mounted from the engine to shock tower. On four cylinder engines, there is a ground strap from the rear of the muffler to the muffler mounting bracket. These ground circuits should be securely tightened to assure good metal to metal contact. Ground straps conduct very small high frequency electrical signals to ground and require clean large surface area contact. The radio grounds to the cross car beam through pinch brackets that grounds automatically as the radio is installed into the instrument panel.

Radio resistance type spark plug cables in the high tension circuit of the ignition system complete the interference suppression. Faulty or deteriorated spark plug wires should be replaced.

Power Antenna
The power operated radio antenna is a telescoping type antenna, extended and retracted by a reversible electric motor.

The Automatic Power Antenna is controlled by a combination of an internal relay and limit switches which, are built into the antenna motor housing. This antenna is actuated when the radio is switched ON and the ignition switch in ON or ACCESSORY position. When the ignition switch or the radio is turned OFF the antenna mast should retract fully.

Many antenna problems may be avoided by frequent cleaning of the antenna mast telescoping sections. Clean the antenna mast sections with a clean soft cloth.

Before an antenna is removed, the antenna performance should be tested to decide if it is a reception problem or an operational problem.

Whenever a operational malfunction occurs, first verify that the radio antenna wire harness is properly connected. Check all connectors before starting normal diagnosis and repair procedures.

Remote Amplifier
The amplifier is located under the right front seat.

When the radio system is ON, and all or some speakers are not operating or have a noise distortion refer to the diagnostic tests.

CIRCUIT OPERATION
Radio Operation
There are two audio systems offered on this vehicle. The base system uses four speakers and a standard antenna. The optional system has six speakers, power amplifier, and a power antenna.

Both systems are powered by a 10 amp fuse located in cavity 14 of the junction block on circuit X12. This fuse is HOT when the ignition switch is in the ACCESSORY or RUN position.

The A31 circuit, which receives it's power from the ignition switch, on circuit A1, is protected by a 20 amp fuse located in cavity 8 of the Power Distribution Center (PDC).

Both the standard and optional radios use an external case ground. This case ground attaches to the rear of the radio and the instrument panel.

Radio Memory
Both the base and premium systems use the M1 circuit to maintain radio memory. This circuit is connected to the battery through the Power Distribution Center (PDC), and protected by a 10 amp Ignition Off Draw (IOD) fuse. The M1 circuit is used to supply power to the Body Control Module (BCM), Power Mirrors, and the Power Door Locks. This fuse is also used in several other circuits. The IOD fuse is removed during vehicle shipping to prevent excessive battery draw.

Radio Illumination
when the parking lamps or the headlamps are ON, circuits E2 and L7 are used to power the radio illumination lamps. Circuit E2 is controlled by the Body Control Module (BCM). Circuit L7 is controlled by the park lamp switch.