Focus ZTS L4-2.0L DOHC VIN 3 (2001)
Information Bus: Description and Operation
Principles and Operation
Module communication is established via two different bus systems; the Data Link Connector (DLC) forms the interface between the modules and the
diagnostic tester.
The data bus Standard Communication Protocol (SCP) consists of two twisted wires. Communication takes place along these wires both between the
modules themselves and between the modules and the diagnostic tester. Even if there is a break in one of the wires or there is a short to ground or short
to power, communication between the modules and the diagnostic tester is still possible on the other wire.
The data bus (ISO 9141) Consists of a single line. If there is a break in the line or there is a short to ground or short to power, then communication
between the module and the diagnostic tester is not possible.
The DLC is a standard 16-pin connector which connects the communication wires (SCP and ISO 9141), the (EEPROM) programming line and the
diagnostic tester power supply.
The steering position sensor passes on the angle of turn of the steering wheel to the Electronic Stability Program (ESP) module and communicates with
the ESP module and the data link connector via the data bus (SCP).
The ESP module controls the anti-lock braking system (ABS). It is connected to the Powertrain Control Module (PCM), the steering position sensor and
the DLC via the data bus (SCP). A connection to the DLC is also possible via (he data bus (ISO 9141).
The ABS module is connected to the DLC via the data bus (ISO 9141).
The vehicle is fitted with either the ESP module or the ABS module.
The PCM controls all functions related to engine management and emission control. This module communicates with the ESP module, the ABS module,
the instrument cluster and the DLC via the data bus (SCP).
The instrument cluster is connected to the DLC and the PCM via the data bus (SCP), and consists of the following components:
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speedometer
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tachometer
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odometer
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trip recorder
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fuel gauge
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engine temperature gauge
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various warning lamps and indicator lamps
The airbag module controls the driver and passenger airbags, the side airbags and the pyrotechnic seat belt pretensioners. The module is connected to the
DLC via the data bus (ISO 9141).
The Central Timer Module (CTM) is connected to the DLC via the data bus (ISO 9i41) and controls time dependant functions for the following systems:
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heated rear window and windscreen
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interior lighting
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front and rear intermittent wipers
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front and rear washers
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seat belt warning
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ignition key removal lock
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power saving relay
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acoustic warning signal
The Central Security Module (CSM) module is connected to the data bus (ISO 9141) and controls the following functions:
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luggage compartment release
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central locking
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audio unit remote control
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anti-theft system
The auxiliary warning system module is connected to the DLC via the data bus (ISO 9141) and controls the following functions:
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washer fluid level low-warning lamp
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outside air temperature display
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ice warning
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fault code display
