S80 L6-2.9L VIN 92 B6294S2 (2004)
In earlier cars each control module handled a particular specific function. Cars with a trip computer required an extra control module to run the trip
computer functions. If a problem arose in a control module it was replaced, regardless of whether the fault was a hardware or a software fault.
As the number of variants and amount of functionality increased, it became both impractical and uneconomic to have one control module per function as
before. A new type of electrical system was required. The new electrical system uses distributed functionality, CAN communication and
re-programmable control modules.
Distributed functionality means that a function need not be connected to a particular control module. A single function can be divided between several
different control modules.
The lock and alarm system function is distributed between the central electronic module (CEM), upper electronic module (UEM), driver information
module(DIM), driver door module (DDM), passenger door module (PDM) and rear electronic module (REM).
The controller area network (CAN) is a high speed digital network, which permits the control units in the car to transmit a large amount of information in
a very short time.
Re-programmable control units permit programming of increased functionality, without needing to replace the control module. This decreases the repair
costs for the customer.
Software downloading has a number of advantages:
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To obtain a new function, for example to add a trip computer to a car without a trip computer, a new control stalk is installed and a new car
configuration file is downloaded into the central electronic module (CEM). The other control modules in the car use the car configuration file to
function in a particular way. The software in the driver information module (DIM), for example, reads off whether the trip computer information is
to be displayed or not depending on the car's level of equipment
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Fewer control module variants. A good example is the engine control module (ECM). There are 60 different engine variants, which previously
required 60 different replacement parts to be stored in the replacement parts stocks. When downloading software, three different hardware
packages manage all the variants
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Market adaptation. The application file for the driver information module (DIM) can be the same for all markets. But other market files can be
downloaded, to separate different market requirements
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Language. The language in the combined instrument panel can be changed by downloading different language files to the driver information
module (DIM)
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This allows faster introduction of improved functionality
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Time saving when working with a particular type of fault. Previously it was necessary to replace a control module. Now a software upgrade can
now be downloaded instead.
NOTE: All data is overwritten during a software download. This includes diagnostic trouble codes (DTCs) and frozen values which were stored.
Software
Software
