Concorde V6-2.7L VIN V (2001)
Body Control Module: Description and Operation
Part 2 of 5
AUDIO SYSTEM
There are radio systems available that communicate on the PCI bus. They use the bus for three reasons. First is to communicate trouble codes to
the body control module, second is to control the remote radio switches located on the back of the steering wheel, and third is for use with the
driver memory selection system. The radio stores two sets of station presets and can be recalled by pressing the optional memory select button
(located on the drivers door). The midline will have 6 speakers and a 120 watt external amplifier. The Infinity I will have 7 speakers and a 240
watt external amplifier or with a in dash 4-disk CD Player. The Infinity II will have 9 speakers and a 360 watt external amplifier with indash
4-disk CD Player. Depending on the manufacturer, some systems have a Front/Rear channel system and others have a Left/Right channel system.
When troubleshooting output shorts or "output" error messages, the following applies:
On radios with out 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. The output DTC could refer to a front or rear output or a left or right output. The reason for the
difference is the pairing of the output sections of the radio. Some are paired left and right, others are paired front and rear.
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.
These radios can be controlled via remote radio switches (optional). These switches are located on the back side of the steering wheel. They
control volume, preset bank selection, seek and scan functions.
These functions are inputs to the body controller and can be read with the DRBIII(R) under "body" systems, sensor displays. The switches are a
multiplexed signal to the BCM. The remote radio control circuit is a five 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 body controller and it sends a specific message to the radio on the PCI bus line. The
radio then responds to the message.
This circuit is fairly simple to troubleshoot. The circuit must be complete from the switches in the steering wheel to the BCM. The ground must be
complete so that the switches can cause the voltage drop for the BCM to see. The circuit passes through the clockspring so continuity throught this
device must be verified.
The new in-dash CD-changer is designed to fit into the existing cubby bin in the center stack. This new cartridge-less CD-changer is controlled by
your radio, and allows you to individually load up to four discs at one time. However, due to its compact design, the CD-changer can only carry
out one operation at a time. For example, you can not load a new disc while playing another at the same time. Each operation happens sequentially.
The radio unit installed with your system provides control over all features of the CD-changer with the exception of the CD load and eject
functions, which are controlled by buttons located on the front of the CD-changer. The radio also supplies the power, ground, PCI Bus, left and
right speaker output thru a single DIN cable. All features you would expect, such as Disc Up/Down, Track Up/Down, Random and Scan are
controlled by the radio, which also displays all relevant CD-changer information on the radio display.
The CD-changer contains a Load/Eject button and an indicator light for each of the four disc positions. The individual light indicates whether a
CD is currently loaded in that particular chamber of the CD-changer. Pressing the individual Load/Eject button for a particular chamber will eject
a disc currently present in that chamber. If the chamber is currently empty, actuating the Load/Eject button will position that chamber to receive
and load a new disc in that chamber.
BODY CONTROL MODULE
The Body Control Module (BCM) supplies vehicle occupants with visual and audible information and controls various vehicle functions. To
provide and receive information, the module is interfaced to the vehicle's serial bus communications network (the Programmable Communication
Interface or PCI bus). This network consists of the Powertrain Control Module (PCM), the Memory Heat Seat/mirror Module (MHSMM), Sentry
Key Immobilizer Module (SKIM), the Transmission Control Module (TCM), the Electro/mechanical Instrument Cluster (MIC), the optional
Overhead Travel Information System (OTIS), Occupant Restraint Control (ORC) module, optional Antilock Brakes (ABS), the radio remote
CD-player, optional left and right airbag control modules, and the optional Automatic Temperature Control (ATC) display head. The (BCM) is
operational when battery power is supplied to the module, ignition switch power is needed for ignition switched functions.
