Mercedes-Benz Sprinter 2003, Manual

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loads are connected to cables and mounted in a
storage case. The cables can be directly connected to
some airbag system connectors. Jumpers are used
to convert the load tool cable connectors to the other
airbag system connectors. The adapters are con-
nected to the module harness connector to open
shorting clips and protect the connector terminal
during testing. When using the load tool follow all of
the safety procedures in the service information for
disconnecting airbag system components. Inspect
the wiring, connector and terminals for damage or
misalignment. Substitute the airbag load tool in
place of a Driver or Passenger Airbag, seat belt
tensioner, clockspring (use a jumper if needed).
Then follow all of the safety procedures in the
service information for connecting airbag system
components. Read the module active DTCs. If the
module reports NO ACTIVE DTCs the defective
components has been removed from the system and
should be replaced. If the DTC is still active, con-
tinue this process until all components in the circuit
have been tested. Then disconnect the module con-
nector 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 conditions.
3.1.6 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 instructions
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
t
. 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.
3.1.6.1 ACTIVE CODES
If the lamp remains on, there could be an active
DTC in the system. The code becomes active as soon
as the malfunction is detected or key-on, whichever
occurs first. An active trouble code indicates an
on-going malfunction. This means that the defect is
currently there every time the airbag control mod-
ule checks that circuit or component. Some DTCs,
Internal Module and squib DTCs, will keep the
indicator illuminated even if they are no longer
active. If the lamp is on and no active codes are
present, cycling the ignition switch off and then on
will refresh the lamp state. It is impossible to erase
an active code.
3.1.6.2 STORED CODES
Airbag codes are automatically stored in the
ACM’s memory as soon as the malfunction is de-
tected. A stored code indicates there was an active
code present at some time. Stored diagnostic trou-
ble code will remain stored until erased by the DRB.
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 inspection. If no obvious
problems are found, erase stored codes, and with
the ignition on wiggle the wire harness and connec-
tors, rotate the steering wheel from stop to stop.
Recheck for codes periodically as you work through
the system. This procedure may uncover a malfunc-
tion that is difficult to locate.
3.2 COMMUNICATION
3.2.1 COMMUNICATION K-LINES
The K-Lines are a group of circuits that connect
each control module to the Data Link Connector
(DLC). Each control module is connected to the DLC
with a single K-Line. The DRBIII
t
uses the K-Line
to communicate with each control module. With the
use of the K-Lines the DRBIII
t
is able to read each
control modules DTCs, sensor displays, I/Os etc. If
DRBIII
t
communications with a particular control
module is lost, one of the possible causes could be a
fault in the module’s K-Line.
NOTE: It is important to note the DRBIII
T
uses the K-Lines for diagnostic and
monitoring functions and is no way
connected to the CAN data bus network.
The following modules that use the K-line on this
vehicle are:
• Airbag Control Module (ACM)
•
Automatic Temperature Control (ATC)
• Cabin Heater Module (CHM)
• Central Timer Module (CTM)
• Controller Antilock Brake (CAB)
• Engine Control Module (ECM)
• Heater Booster Module (HBM)
• Instrument Cluster (IC)
•
Shifter Assembly (SA)
• Security System Module (SSM)
•
Sentry Key Remote Entry Module (SKREEM)
• Transmission Control Module (TCM)
4
GENERAL INFORMATION