ESP RENAULT SCENIC 2008 J84 / 2.G Electrical Equipment - Multiplexing Workshop Manual

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MULTIPLEXING
Fault finding - Introduction
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V4 MR-372-J84-88B050$100_eng.mif
COMPUTERS
–Valid: green border, green lettering.
–Not detected: red border, red lettering.
–Do not support fault finding: black border, black lettering.
–Not recognised: red border, red lettering + exclamation mark.
SEGMENTS
–Valid: green dash.
–Faulty: red dash.
–Cannot support fault finding: black dash.
INTERPRETING TEST RESULT CHARTS
On the Problems tab, the computers are organised into the following groups:
–Not detected if the computer failed to respond to the tool's identification request.
–Within the not detected category, the computers are subdivided into Stores multiplex network configuration
and Does not store multiplex network configuration.
–Not recognised if the computer is detected but cannot be identified from its response.
On the Information tab, the computers are organised and listed as follows:
–Cannot support fault finding, if the computer cannot support fault finding with the tool and therefore was not
queried.
–Valid if the computer responded correctly to the tool's request.
If the Proceed icon in the bottom right-hand corner is selected, a new screen will appear with the following tab:
Under the Results tab the computers are organised into the following groups:
–Faulty if the computer is recognised and has a non-zero number of faults.
–OK if the computer was detected, recognised and has no faults.
–Not recognised if the computer was detected but could not be identified from its response.
–Not detected if the computer can support fault finding but failed to respond.
FUNCTION TESTING
The vehicle function tests screen resembles the multiplex network test screen in showing a diagram of the network
architecture if this is known and displayed.
The Function tab displays the various computers involved in the functions whether distributed or not distributed over
the various computers.
The Info tab displays the other possible functions found on the vehicle concerned.
Selecting a function from the list greys out the computers on the diagram that are not involved in that function.
The Fault finding button runs fault finding on the function selected from the list.

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MULTIPLEXING
Fault finding - Introduction
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REPAIR HELP:
●Assistance with computer or faulty segment detection:
If the multiplex network is completely frozen, this command can isolate multiplex network segments and thereby
rule out those that respond correctly to the tool. This makes it easier to pinpoint the cause of the fault.
The algorithm for help with locating faults is intended for dealing with electrical faults present solely on the multiplex
line; it is therefore essential that connectors and computers not attached to the bus are not taken into consideration.
●A test for multiplex network faults by using physical measurements:
When a multiplex network segment has a short circuit, the computers can no longer communicate with each other or
using the diagnostic tool. At this point, the network test is not operational.
The CLIP tool can identify several types of faults by taking electrical measurements on the multiplex line H and
multiplex line L multiplex network. It can detect a multiplex line L/multiplex line H short circuit, a multiplex line
L/+ 12 V short circuit, a multiplex line H/+ 12 V short circuit, and a multiplex line H/earth short circuit.
Then, by disconnecting the connectors and computers in the order described under the "Help with detecting faulty
segments - computers" heading, identify the actual or possible segment causing the multiplex network fault.

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MULTIPLEXING
Fault finding - Introduction
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MULTIPLEXING
Multiplexing enables signals to be sent between different computers on the vehicle, such as:
1UPC.
2Injection computer.
3BVA computer.
4LPG or CNG computer.
5ABS/ESP computer.
6UCH.
7Electric steering column lock.
8Automatic parking brake computer.
9Parking distance control computer (depending on version).
10 Electric power-assisted steering system.
11 Instrument panel.
12 Diagnostic socket.
13 ITS or Multimedia interface unit (depending on version).
14 Climate control computer.
15 Driving school unit (depending on vehicle).
16 Airbag/pretensioner computer.
MR-372-J84-88B050$200_eng.mif

MULTIPLEXING
Fault finding - Operating diagram
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MULTIPLEXING
Fault finding - Operating diagram
1UPC.
2Injection computer.
3BVA computer.
4LPG or CNG computer.
5ABS/ESP computer.
6UCH.
7Electric steering column lock.
8Automatic parking brake computer.
9Parking distance control computer (depending on
version).
10Electric power-assisted steering system.
11Instrument panel.
12Diagnostic socket.
13ITS or Multimedia interface unit (depending on
version).
14Climate control computer.
15Driving school unit (depending on vehicle).
16Airbag/pretensioner computer.
MR-372-J84-88B050$300_eng.mif

MULTIPLEXING
Fault finding - Features
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1) The transmitting computer formats the signal to be
transmitted into a frame that can be identified by
other computers.
2) The transmitting computer waits for the network to
be free, i.e. no frames are being transmitted by
another computer.
3) The computer can then transmit its frame.
4) All the other computers receive the transmitted
frame. As the frame has already been formatted
by the transmitting computer, the receiving
computer can determine whether the frame was
meant for it or not.
5) The receiving computers acknowledge the frame
to confirm that the frame has been received. The
transmitting computer will resend the frame if it
does not receive this acknowledgement.
Transmitting frames
The frames are transmitted on two twisted wires in
order to avoid electromagnetic interference. These
wires are called multiplex line H and multiplex line L.
To reduce electrical interference when frames are sent,
the two wires have differential voltages. In addition,
terminating resistances of 120 Ω are fitted at the ends
of the network (in the airbag and injection computers)
to attenuate electrical signal reflections.
The electric signals are digital which means that there
can only be two levels of differential voltage known as
recessive status (corresponding to logic 1) and
dominant status (corresponding to logic 0).
The status is recessive when the potential difference
between multiplex line H and multiplex line L is zero
(multiplex line H = multiplex line L = 2.5 V). The status
is dominant when the potential difference between
multiplex line H and multiplex line L is equal to
approximately 2 V (multiplex line H = 3.5 V and
multiplex line L = 1.5 V).
Content of the frame
A multiplex line frame comprises several groups of
contiguous bits:1A field indicating the start of the frame.
2An arbitration field with a destination code so that
receiving computers can recognise the frame. In
addition, this field decides on frame priority when
several computer want to send a frame at the
same time.
3A test field which supplies various information
about a frame.
4A field containing the data to be transmitted.
5A frame confirmation field which ensures that the
signal is correctly transmitted as well as the
acknowledgement indicating that the frame has
been correctly received.
6A field indicating the end of the frame.
Fault finding
Multiplex computers fitted with diagnostic connections
have multiplex network fault finding systems.
Each computer monitors its capacity to send and
receive frames to and from other computers. Any
observed fault is revealed by one or several present or
stored faults on the multiplex network. These faults are
grouped under a format common to all computers and
are communicated via a special frame to the
diagnostic tool.
In the After-Sales Centre, these faults can be viewed
on a diagnostic tool in order to identify the faulty
connections(s) between computers and to deduce the
fault type and its location.
The diagnostic tool always runs a multiplex network
test when it is connected to the vehicle.

MULTIPLEXING
Fault finding - Defect and safe modes
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MULTIPLEXING
Fault finding - Defect and safe modes
The multiplexing function does not have a safe mode
program.
However, the multiplexing function may have special
operation features.
The multiplex network still functions when multiplex
line L is in short circuit to earth. The voltage on
multiplex line H is no longer differential; it corresponds
to earth.
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MULTIPLEXING
Fault finding - Configuration
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Configuration screen
Make sure that the information displayed on the two tabs is correct.
The same configuration information for the two computers is essential for displaying the network topology.
Computer Multiplex network configurationConfiguration of computers that
can support fault finding
Injection PRESENT YES
ABS or ABS/ESP PRESENT YES
UCH PRESENT YES
Automatic gearbox connection PRESENT or ABSENT (option) YES or NO (option)
Instrument panel PRESENT YES
LPG PRESENT or ABSENT (option) YES or NO (option)
Steering lock PRESENT NO
Electric power-assisted steering PRESENT YES
Protection and Switching Unit PRESENT YES
Climate control (regulated) PRESENT or ABSENT (option) YES or NO (option)
Central Communication Unit* PRESENT or ABSENT (option) YES or NO (option)
Driving school unit PRESENT or ABSENT (option) NO (cannot support fault finding)
Airbag PRESENT YES
Automatic parking brake PRESENT or ABSENT (option) YES or NO (option)
Parking Distance Control** PRESENT or ABSENT (option) YES or NO (option)
Xenon bulbs ABSENT YES or NO (option)
Radio*** ABSENT YES
Multimedia interface*** PRESENT YES
*IMPORTANT:
NAV 4R ABSENT YES
ITS PRESENT YES
Others ABSENT NO

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Fault finding - Configuration
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Option: depending on equipment level
If during the multiplex network test the following message appears: No dialogue established with some computers:
check power supply and diagnostic lines before starting the test again.
–This does not prevent the multiplex network from being viewed.
–Check if too many computers have not been listed in the configuration: update the multiplex network according to
the table above. **Note:
The parking distance control is present on the multiplex network when it is fitted to the front and rear of the vehicle
(Vdiag OC only).
It is not present on the multiplex network if it is only fitted to the rear of the vehicle.
***Note:
The radio computers (which correspond to the LPN navigation) and the Multimedia Interface listed above must only
be configured with the LPN navigation (diagram version number = 04)

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MULTIPLEXING
Fault finding - Interpretation of faults
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FAULTY COMPUTER
NOTES–Make sure the computers installed in the vehicle are the correct type and are
compatible with the Scénic II ph2.
–Check the power supply of the computers (earth, + battery, + accessories or + after
ignition).
Make sure that the computer wake-up mode is in full working order on the vehicle and properly assimilated by the
computers.
The wake-up mode is:
–timed power supply: UCH, instrument panel.
–+ accessories feed: Protection and Switching Unit, Heating and Air Conditioning System, Central
Communication Unit.
–+ After ignition feed: Injection, ABS/ESP, airbag, Electric Power-Assisted Steering, Automatic
Transmission, LPG/Natural Gas Fuel, Steering column lock, Driving School Unit, Automatic Parking
Brake, Parking Distance Control.
–+ After ignition + dipped headlights: Xenon bulbs.
IMPORTANT
Only establish dialogue with the discharge bulbs with + after ignition and the dipped headlights on.
–Switch to computer diagnostics mode.
Attempt to establish dialogue with computers.
●No dialogue from computers to diagnostic tool: see ALP 1
No dialogue with the computer or computers not communicating with the diagnostic tool.
Check the connections to the computers and that there are no open circuits.
If there is a repair procedure (see Technical Note 6015A, Repairing electrical wiring, wiring:
precautions for repairs), repair the connectors, otherwise change them.
●The computers only produce partial information when identified:
Check in the MR or World Vehicle Database to see that the computer really is compatible with the
Scénic II ph2.
Make sure the CLIP diagnostic tool update is recent enough to handle Scénic II ph2 faults.
If after these tests no faults or open or short circuits have been detected, contact your Techline.
AFTER REPAIRRun the multiplex network test again using the diagnostic tool.
Clear the stored faults on all the computers connected to the network.
Deal with any other faults.

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MULTIPLEXING
Fault finding - Fault Finding Chart
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ALP 2No topology diagram or configuration table display at the end of
the multiplex network test
The topology cannot be displayed under the following conditions:
1. The two computers storing the multiplex network configuration have failed to respond.
2. The multiplex network is not operational, therefore dialogue is impossible.
3. The two computers storing the multiplex network configuration do not have the same configurations.
4. On the multiplex network tab on the configuration screen, an incorrect network version number has been
entered on one of the two computers storing the network configuration.
5. No network version has been entered on the two computers that store the configuration.
1 – The two computers storing the multiplex network configuration have failed to respond.
Check first that the computers storing the configuration (Airbag and UCH) are correctly supplied (earth,
+ battery, + accessories or + after ignition).
Check the condition of the multiplex network and the continuity and insulation of the multiplex line H and
multiplex line L lines between the computers storing the configuration.
2 – The multiplex network is not operational, therefore dialogue is impossible (see Network not
operational fault).
3 – The two computers that store the multiplex network configuration do not have the same configurations
(see Network configurations configuration).
4 – On the multiplex network tab on the configuration screen, an incorrect network version has been
entered on one of the two computers storing the network configuration (see Network configurations
configuration).
5 – No diagram version has been entered into the two calculators that store the configuration (see Network
configurations configuration).