RAM 2500 Truck 2WD V8-5.7L VIN D (2004)
radio are used for VF dimming and remote steering wheel controls. All the radios are capable of displaying faults and allowing certain actuation tests
through the use of the DRBIII(R). When attempting to perform PCI Bus diagnostics, the first step is to identify the radio in use in the vehicle.
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.
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(R). 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.
AMPLIFIER (PREMIUM SYSTEM)
The Premium Audio Amplifier uses a microprocessor for audio digital signal processing (DSP) and system diagnostics. DSP provides a more accurate
and consistent match of the audio system equalization 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(R) 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 diagnostic
functions. Tests can be run from the DRBIII(R) that will help in diagnosing audio system problems. The DRBIII(R) 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(R) can be used to verify the amplifier equalization setting matches the
vehicle, in case there is a sound quality complaint. Using the DRBIII(R) audio system diagnostics can determine the nature of the problem.
Diagnostic tests the Amplifier can perform through the DRBIII(R):
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
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
information is supplied through a DVD-ROM. An electronic 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.
Communication
The Programmable Communication Interface or PCI Bus is a single wire multiplexed network capable 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
different module connections. The modules are wired in parallel. Connections are made in the harness using splices. The following modules are used on
this vehicle:
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Front Control Module
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Airbag Control Module
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Controller Antilock Brake
