Pontiac Fiero 1988 Service Manual page 1163

RADIO
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CIRCUIT OPERATION
The Radio Fuse provides main power to the
Radio and to the Power Antenna. With the
Ignition Switch in ACCY or RUN, voltage is
applied to the Radio Fuse and the YEL wire to
the On-Off Switch in the Radio. The circuit is
grounded at G201. With the On-Off Switch
closed, voltage is applied to the Radio Fuse,
Radio Switch (Power Antenna), and the Solid-
State Radio circuits to ground. Two wires con-
nect each speaker to the Radio.
The ETR Radio has two inputs that other
models do not have: Dim Display Signal and
Clock Power.
The ETR model is an AM/FM Radio that
changes stations electronically. The frequencies
of pre-selected stations can be stored in the
electronic memory. The ETR model also pro-
vides digital display of time or station frequency.
As in other models, the Light Switch controls
panel light dimming. In the ETR model, dim-
ming is also controlled by the Radio itself by
means of the Dim Display Input Signal.
The ETR model's clock memory and Radio
memory functions are powered at all times
through the BAT Fuse. If power to the ETR
model is cut off by disconnecting the Battery, for
example, the operator must reset the memory
functions when power is restored.
The Subwoofer Speaker System consists of a
Subwoofer Amplifier, Subwoofer Speaker and a
Performance Sound Control located in the Dome
Lights Module. Voltage is applied to the Sub-
woofer Amplifier at terminals 3 and 13 whenever
the Radio is on. The Amplifier is grounded at
G201 at terminal 14. There are eight audio inputs
to the Subwoofer Amplifier from the Radio
Audio Outputs. Amplifier gain is controlled by
the Performance Sound Control. The Subwoofer
Amplifier applies a signal voltage of 8 volts to the
Performance Sound Control. The gain voltage
will vary between 3.5 and 8.0 volts at terminal 9
as the Performance Sound Control is moved
between the Minimum and Maximum positions.
The Subwoofer Amplifier then adjusts the audio
output to the Subwoofer Speaker.