lock RENAULT TWINGO RS 2009 2.G Electrical Equipment - Multiplexing Workshop Manual

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INTRODUCTION
Description of the multiplex network:
The multiplex network consists of a twisted pair of wires connected to several vehicle computers.
These two wires are called multiplex line H and multiplex line L.
Depending on the vehicle options, there is a single multiplex network.
–the Vehicle multiplex line (injection, anti-lock braking system/electronic stability program, instrument panel, air
conditioning, rev counter, sequential gearbox, UCH, airbag/pretensioners) is always present,
–the Multimedia multiplex line (navigation, radio, display, hands-free telephone) depending on the vehicle options.
Data is exchanged by the computers on the Vehicle multiplex line and Multimedia multiplex line networks at a
communication speed of 500 kbit/s.
The Vehicle multiplex line network has two computers, each with an internal resistance of 120ΩΩ Ω Ω

(network terminating resistors):
–the injection computer,
–the airbag computer.
The Multimedia multiplex line network has two computers, each with an internal resistance of 120ΩΩ Ω Ω

(network terminating resistors):
–the A2/A3 display,
–the radio.
PURPOSE
–The purpose of the multiplex network test is to determine the computers present on the vehicle's multiplex network
as well as the cause of possible inter-computer communication faults.
–It also serves to determine the functions installed in the vehicle which are often housed in various computers
(distributed functions, e.g.: Air conditioning, Security access, etc.).
–The test also checks the condition of multiplex network segments.
–The multiplex network test can also run fault finding on computers disconnected from the multiplex network; this
provides an overview of the vehicle's electronic layout. Note:
The Vehicle and Multimedia multiplex line networks support fault finding using the RENAULT tool.
MULTIPLEXING
Fault finding – Introduction

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To improve the performances of vehicles, more computers are needed to share more information in order to achieve
optimal operation.
With multiplexing, numerous signals can be sent from one computer to several others via a single electrical
connection.
Solution without multiplexing
Example: each computer should have its own electrical connection in order to use the vehicle speed signal sent by
the anti-lock braking system vehicle speed computer (depending on vehicle equipment). The number of connections
increases when there are more signals to be communicated.1ABS computer3Instrument panel
2Automatic gearbox computer4Injection computer
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MULTIPLEXING
Fault finding – Function

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MULTIPLEXING
Fault finding – Function88B
Solution with multiplexing
In this case, the vehicle speed signal is shared by the anti-lock braking system vehicle speed computer (depending
on vehicle equipment), and as many computers as necessary via a single electrical connection. All other signals are
transmitted via this connection as well. Thus there is only one connection regardless of the number of signals to be
exchanged.
Advantages of multiplexing
•Reduction in costs as there is a reduction in wire length and there are fewer connectors.
•Less weight due to wiring harness.
•Increased reliability due to there being fewer connectors.
•Easier to locate a faulty component in some cases.
Multiplex operation
The operation of a multiplex network can be compared to an underground line which transports a number of
passengers. All the passengers use the same line even though they get on and off at different points and they take
different trains depending on when they started their journeys.1ABS computer3Instrument panel
2Automatic gearbox computer4Injection computer
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