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

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188BMULTIPLEXING
Fault finding - Introduction
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.
Two of the computers have an internal resistance of 120 Ω (terminating resistance):
–the airbag computer,
–the injection computer:
The network carries data exchanged by the computers.
The Scénic II ph2 is a new generation multiplex vehicle; the main change is the increase in communication speed
to 500 kBauds.
On the Scénic II ph2, fault finding can only be performed on one multiplex network with the RENAULT tool.
The maximum number of computers on this network is 15.
PURPOSE
●The purpose of the multiplex network test is to determine the various 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 sometimes housed in various
computers (distributed functions).
●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. IMPORTANT
Fault finding can only be carried out on Scénic II ph2 using the CLIP diagnostic tool equipped with the new
vehicle connection probe cord (Part no.: Elé 1674 or 00 00 167 400).
Note:
A second multiplex network for the navigation system may also be present.
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MULTIPLEX NETWORK OPERATION TEST
This step is the essential starting point for any computer fault finding procedure.
It ensures that the network is correctly connected at the terminals of each computer and that the signal is correctly
sent to it and received by it. On the Scénic II ph2, this function also reads the number of faults present on the
computers.
The multiplex network test function is executed automatically after vehicle selection by the user.
After the network check, the other functions become accessible.
MULTIPLEX NETWORK TEST PROCEDURE
–Establish dialogue with the computers storing the vehicle configuration (read identification).
–Vehicle configuration read on the two computers that hold the multiplex network configuration (airbag and UCH
on the SCENIC II ph2).
–List of computers that can support fault finding read from the two computers that hold the multiplex network
configuration.
–Computer interrogation.
–Physical (electronic) measurements on the multiplex line network. Vehicle computer power supply for fault finding:
insert the vehicle card in the card reader.
Press and hold (over 5 seconds) the Start button in the absence of start conditions (for example: selecting a gear).
Connect the diagnostic tool and perform the required operations.
IMPORTANT
To supply the discharge bulb computer, switch on the dipped headlights.

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MULTIPLEXING
Fault finding - Interpretation of faults
FAULTY SEGMENT ON THE MULTIPLEX NETWORK
NOTESFirst check that the computer at the end of the faulty segment is properly
powered (earth, + battery, + accessories or + after ignition).
Always check the computer conformity.
If the Protection and Switching Unit computer is not detected, apply the appropriate
fault finding procedure (see 87G, Engine Compartment Connection Unit, Fault
Finding Chart, ALP1).
IMPORTANT
The tool may not be able to pinpoint the faulty segment(s) exactly. It then suggests
several segments that could be faulty. In this event, repair the segment closest to the
diagnostic socket.
Isolate the faulty segment by disconnecting both ends of the segment. Check the condition of the connections (see
Technical Note 6015A Repairing electrical wiring, Multiplex: Multiplex network, Repair).
Check the continuity and insulation of the multiplex line H and multiplex line L lines between the two connectors
on the isolated segment.
Refer to the vehicle's multiplex network diagram for the allocation of tracks on the computers and connections.
Perform the necessary operations to check the continuity of the two lines (for example, replacing the wiring).
Make sure that the computer present in the vehicle is compatible with the Scénic II ph2 and that the signals it is
producing are correct.
Reconnect the segment.
Run the multiplex network test again using the diagnostic tool.
Is the segment still declared faulty?
NoEnd of fault finding.
Are there other faulty segments?
Yes
NoTest the multiplex network again to check the continuity and
insulation of the multiplex line H and multiplex line L lines
between the end of the faulty segment and the diagnostic
socket at connections 133B and 133C (see diagnostic
socket diagram).
Apply the same procedure to each segment.
Yes
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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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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ALP 1
CONTINUED 3
NOTESVehicle computer power supply for fault finding:
insert the vehicle card in the card reader.
Press and hold (over 5 seconds) the Start button in the absence of start conditions (for
example: selecting a gear).
Connect the diagnostic tool and perform the required operations.
IMPORTANT
To supply the discharge bulb computers, switch on the dipped headlights.
Use Technical Note Wiring diagram, Scénic II ph2.
Check the following connections on the diagnostic socket:
BP 32 + battery feed
NAM and MAM Earth
If the connection or connections are faulty and there is a repair procedure (see Technical Note 6015A, Electrical
wiring repair, Wiring: Precautions for repair), repair the wiring, otherwise replace it.
Computer connected to multiplex line V
If the fault is still present, check the continuity and the insulation of the following connections:
Multiplex line H (133B of component 225)
Multiplex line L (133C of component 225)
Use a multimeter to check that the voltages at the terminals of component 225 are approximately:
–2.5 V between multiplex line H (133B) and the earth (NAM and MAM) (Average values)
–2.5 V between multiplex line L (133C) and the earth (NAM and MAM) (Average values).
Refer to the Introduction - “Repair advice” to detect a short circuit on the vehicle's multiplex network.

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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).

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ALP 3Configuration table display at the end of the
multiplex network test
NOTESALP to use if the tool loads the configuration screen at the end of the multiplex network
test.
The configuration chart is always accessible through the Configuration icon.
Update the vehicle configuration then run the multiplex network test again.
Check that the two tabs are consistent before running the test again.
The CLIP diagnostic tool loads the configuration screen directly under the following conditions:
●MULTIPLEX NETWORK tab
–Inconsistency between the network version numbers entered into the two computers that store the
multiplex network configuration. If the numbers are inconsistent, the following error message is
displayed when the multiplex network test is being run: Inconsistent configuration of computers
supporting fault finding: check configuration before rerunning test.
–Inconsistent list of computers entered into the computers that store the multiplex network configuration.
–The diagram version number is incorrect for at least one of the two computers that store the multiplex
network configuration (see the Network configurations configuration).
–In this instance, the following message is displayed when the multiplex network test is being run:
Unknown vehicle configuration: check tool update.
–One of the two computers that store the network version is blank (case of replaced airbag or UCH
computer).
●COMPUTERS SUPPORTING FAULT FINDING tab
–Inconsistent diagram numbers entered into the two computers that store the configuration.
–Inconsistency in the list of computers that can support fault finding entered into the two computers that
store the list of computers that can support fault finding.
–Inconsistency between the list of computers entered and the computers actually detected on the
vehicle. Some computers are entered as absent in the computer that stores the network configuration
even though they are present on the vehicle (see the Multiplex network configurations
configuration). In this instance, the following error message is displayed when the multiplex network
test is being run: Some computers respond to the diagnostic tool even if they are not listed in the
computer configuration.