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GENERAL INFORMATION
active, continue this process until all components
in the circuit have been tested. Then disconnect the
module connector and connect the matching
adapter to the module connector. With all airbags
disconnected and the adapter installed the squib
wiring can be tested for open and shorted condi-
tions.
3.2.9 DIAGNOSTIC TROUBLE CODES
Airbag diagnostic trouble codes consist of active
and stored codes. If more than one code exists,
diagnostic priority should be given to the active
codes. Each diagnostic trouble code is diagnosed by
following a specific testing procedure. The diagnos-
tic test procedures contain step-by-step instruc-
tions for determining the cause of the trouble
codes. It is not necessary to perform all of the tests
in this book to diagnose an individual code. Always
begin by reading the diagnostic trouble codes with
the DRBIII. This will direct you to the specific
test(s) that must be performed. In certain test
procedures within this manual, diagnostic trouble
codes are used as a diagnostic tool.
3.2.9.1 ACTIVE CODES
The code becomes active as soon as the malfunc-
tion is detected or key-on, whichever occurs first.
An active trouble code indicates an on-going mal-
function. This means that the defect is currently
there every time the airbag control module checks
that circuit or component. It is impossible to erase
an active code. Active diagnostic trouble codes for
the airbag system are not permanent and will
change within 12 seconds the reason for the code is
corrected. With the exception of the warning lamp
trouble codes or malfunctions, when a malfunction
is detected, the airbag lamp remains lit for a
minimum of 12 seconds or as long as the malfunc-
tion is present.
3.2.9.2 STORED CODES
Airbag codes are automatically stored in the
ACM's memory as soon as the malfunction is
detected. A stored code indicates there was an
active code present at some time. When a trouble
code occurs, the airbag warning indicator illumi-
nates for 12 seconds minimum (even if the problem
existed for less than 12 seconds). The code is
stored, along with the time in minutes it was
active, and the number of times the ignition has
been cycled since the problem was last detected.
The minimum time shown for any code will be one
minute, even if the code was actually present for
less than one minute. Thus, the time shown for a
code that was present for two minutes 13 seconds,
for example, would be three minutes. If a malfunc-
tion is detected a diagnostic trouble code is stored
and will remain stored. When and if the malfunc-
tion ceases to exist, an ignition cycle count will be
initiated for that code. If the ignition cycle count
reaches 254 without a reoccurrence of the same
malfunction, the diagnostic trouble code is erased
and that ignition cycle counter is reset to zero. If
the malfunction reoccurs before the count reaches
254, then the ignition cycle counter will be reset
and diagnostic trouble code will continue to be a
stored code. If a malfunction is not active while
performing a diagnostic test procedure, the active
code diagnostic test will not locate the source of the
problem. In this case, the stored code can indicate
an area to inspect. Maintain a safe distance from
all airbags while performing the following inspec-
tion. If no obvious problems are found, erase stored
codes, and with the ignition on wiggle the wire
harness and connectors, rotate the steering wheel
from stop to stop. Recheck for codes periodically as
you work through the system. This procedure may
uncover a malfunction that is difficult to locate.
3.3 AUDIO SYSTEM
Both the RAH and RBP radios are on the PCI
Bus system. The audio output signal from the
radios, on these central amplifier systems, is fixed
at one volume level (level 25 for RAH and 26 for
RBP). The actual volume, fade, balance, and tone
adjustments are managed via messages sent over
the PCI Bus from the radio to the amplifier which
changes its speaker outputs to the corresponding
settings. The amplifiers will also adjust volume
based on speed messages received over the bus
from the PCM. This keeps the sound level essen-
tially constant relative to the interior noise level at
all driving speeds.
Both the 6-channel base amplifier and the
8-channel surround sound amplifier perform digi-
tal signal processing and contain unique equaliza-
tion curves in their memory. The specific audio
source determines how the amplifier equalizes the
individual channel outputs. Separate EQ's are pro-
vided for AM radio, FM radio, Tape, CD, and DVD
video. There is a sixth EQ ''slot'' available for a TBD
future input source. Audio signal EQ selection is
based on bus messages received from the radio and
Navigation unit. For example, DVD video is equal-
ized for viewing video in the second and third row
seats. Hands-free audio is processed using the AM
radio EQ. Navigation audio is processed based on
the current audio source EQ. The amplifier allows
audio inputs from navigation and hands-free mod-
ule to override whatever else might be playing at
the time. The amplifier provides an independent
output channels to each speaker location: 1) left
front door, 2) right front door, 3) I/P center, 4) right
rear door and 5) left rear door. On eight channel
8
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