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GENERAL INFORMATION
When trouble shooting output shorts or "output"
error messages, the following applies:
On radios without an external amplifier, the term
output refers to the path between the radio and the
speaker. This type of circuit can be monitored all
the way through the speaker connections by the
radio assembly. When the radio displays a shorted
output DTC with this type of system, the speaker,
radio, or wiring could be at fault.
On radios with an external amplifier, the term
"output" refers to the circuit between the radio
connector and the amplifier. The radio is capable of
monitoring only this portion and can tell nothing
about the circuit between the amplifier and the
speakers. Consequently, a shorted output DTC on
this type of system would only refer to this circuit.
A faulty speaker could not cause this DTC.
3.2.1 REMOTE RADIO CONTROLS
These radios can be controlled via remote radio
switches (optional). These switches are located on
the back side of the steering wheel. They control
mode, preset, seek up, seek down, volume up and
volume down functions.
These functions are inputs to the Instrument
Cluster (MIC) and can be read with the DRBIII .
The switches are a multiplexed signal to the MIC.
The radio control MUX circuit is a 5 volt line that is
pulled to ground through different value resistors
built into the switches. This causes a voltage drop to
be seen by the MIC and it sends a specific message
to the radio on the PCI Bus circuit. The radio then
responses to the message.
This circuit is fairly simple to troubleshoot. The
circuit must be complete from the switches in the
steering wheel to the MIC. The ground must be
complete so that the switches can cause the voltage
drop for the MIC to see. The circuit passes through
the clockspring so continuity through this devise
must be verified.
3.2.2 AMPLIFIER (PREMIUM SYSTEM)
The Premium Audio Amplifier uses a micropro-
cessor for audio digital signal processing (DSP) and
system diagnostics. DSP provides a more accurate
and consistent match of the audio system equaliza-
tion to the vehicle interior. The DR Ram amplifier
has six channels for superior sound quality.
The amplifier reads the VIN from the PCI bus
and sets itself to match the vehicle. The amplifier
will send four beeps to the vehicle speakers at
ignition on, if it does not read the VIN correctly. A
replacement amplifier may beep at the first power
up, but if these beeps are heard after the first
ignition on, the DRBIII should be used to verify
the amplifier is connected to the PCI bus and that
the VIN on the PCI bus is correct.
The amplifier, wiring to the speakers and the
speakers work independently from the radio. The
amplifier's microprocessor supports several diag-
nostic functions. Tests can be run from the DRBIII
that will help in diagnosing audio system problems.
The DRBIII can display fault messages when an
input or output problem to the amplifier is detected.
The amplifier can detect wiring shorts and suggest
which wires are likely to be shorted. The amplifier
can send test signals that can be used to verify that
the amplifier, speakers, and wiring to the speakers
are operating properly. The amplifier can also be
used to test if the radio is sending audio signals to
it. The DRBIII can be used to verify the amplifier
equalization setting matches the vehicle, in case
there is a sound quality complaint. Using the
DRBIII audio system diagnostics can determine
the nature of the problem.
Diagnostic tests the Amplifier can perform
through the DRBIII :
Continuous Tone Test - This test will send a
continuous tone to each speaker and will verify the
integrity of an individual channel.
PCI Amplifier Test - This test will detect a PCI
bus or checksum failure.
Input Test - This test will detect the activity on the
amplifiers input channels from the radio.
Speaker Output Test - This test will detect the
activity on the amplifiers output channels to the
speakers.
3.2.3 NAVIGATION RADIO
The optional navigation radio system receives
GPS signals from up to eight satellites to display
the position and direction of the vehicle. Map infor-
mation is supplied through a DVD-ROM. An elec-
tronic gyrosensor and the vehicle's speed sensor
enable the system to display the present vehicle
position even in locations where GPS signals may
be blocked.
When a destination is selected, the navigation
system uses information from the map to quickly
calculate a route. As the vehicle is driven along the
chosen route, the operator is guided with pictorial
displays and voice prompts. For complete operating
instructions, refer to the manual included with the
vehicle.
3.3 COMMUNICATION
The Programmable Communication Interface or
PCI Bus is a single wire multiplexed network capa-
ble of supporting binary encoded messages shared
between multiple modules. The PCI bus circuit is
identified as D25. Additional tracer colors may be
added to the violet in order to distinguish between
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