airbag RENAULT SCENIC 2006 J84 / 2.G Electrical Equipment - Multiplexing Workshop Manual

MULTIPLEXING
Fault finding - Introduction
88B
88B-1
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. The two wires are
known as Can H and Can 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 is a new-generation multiplex vehicle; the main change is the increase in communication speed to
500 kBauds.
On the Scénic II, only one multiplex network can be diagnosed 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 failures.
●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 diagnostics on computers disconnected from the multiplex network; this
provides an overview of the vehicles electronic architecture. WARNING
Fault-finding on the Scénic II can only be done with the CLIP diagnostic tool fitted 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.

MULTIPLEXING
Fault finding - Introduction
88B
88B-2
MONITORING MULTIPLEX NETWORK OPERATION
This step is the essential starting point before any computer diagnostics.
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, this function also reads the number of faults present in 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:
⇒
Communication established with the computers storing the vehicle configuration (identification read).
⇒
Vehicle configuration read in the two computers that hold the multiplex network configuration (airbag and
UCH on the SCENIC II)
⇒ List of diagnosable computers read in the two configuration computers
⇒ Computer interrogation
⇒ Physical (electronic) measurements on the CAN network. Vehicle computer power supply for diagnostics:
Vehicle card in 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 power the discharge bulb computers, the dipped headlights must be turned on.

MULTIPLEXING
Fault finding - Configuration
88B
88B-4
Fault finding - Configuration
MULTIPLEX NETWORK CONFIGURATION
In this vehicle, the two computers holding the multiplex network configuration are the airbag and UCH computers.
The Configuration screen consists of two tabs for displaying and modifying the:
–multiplex network configuration on the first tab,
–diagnosable computer configuration on the second.
LIST OF VEHICLE COMPUTERSWARNING
First repair the computers containing the multiplex network configuration (airbag and UCH) to be able to
display the screen with the multiplex network configuration diagram for the diagnosed vehicle.
ComputerMultiplex network
configurationDiagnosable
computer configuration
Via CANVia the ISO K/L
lines
InjectionPRESENT YES -
ABSPRESENT YES -
Protection and Switching UnitPRESENT YES -
Automatic gearboxPRESENT - YES
LPGPRESENT - YES
Steering lockPRESENT - -
Electric power-assisted steeringPRESENT YES -
Instrument panelPRESENT YES -
UCHPRESENT YES -
Air conditioningPRESENT YES -
Central Communications UnitPRESENT NO NO
Driving school unitPRESENT NO NO
AirbagPRESENT YES -
Automatic parking brakePRESENT - YES
Parking assistanceABSENT NO NO
Discharge bulbsABSENT - YES

MULTIPLEXING
Fault finding - Configuration
88B
88B-5
MULTIPLEX NETWORK GENERIC ARCHITECTURE
Number of multiplex network segments between computers:
* A vehicle can have either LPG or automatic transmission, but never both.
** The vehicle either has just ABS or ABS + ESP (electronic stability program). 120 Injection
118 ABS **
1094 ABS+ESP **
1337 Switching Protection Unit
119 Automatic transmission *
997 LPG / GNV *
1088 Steering lock
1232 Electric power-assisted steering
247 Instrument panel
645 UCH 419 Air conditioning
1125 Control and Communications Unit
469 Driving School Unit
756 Airbag
1217 Automatic parking brake
989 Discharge bulbs
1222 Parking assistance

MULTIPLEXING
Fault finding - Configuration
88B
88B-6
NETWORK CONFIGURATION
NOTESThe configuration is detected with the ignition on.
It can be launched from the multiplex network test results screens.
The tool displays the UCH and/or airbag computer configuration.
Configuration involves the following steps:
–Select the computer to be modified.
–Select the multiplex network diagram version.
The version number increases with each change to the multiplex network wiring in this vehicle.
This information is available in the global vehicle base.
Choice of computers in the vehicle present on the network
The following computers are always fitted to the vehicle:
–Injection
–Protection and Switching Unit
–ABS
–Steering lock (cannot be support fault finding with the tool)
–Instrument panel
–Passenger Compartment Control Unit (UCH)
–Electric power-assisted steering
–Airbag
+ the vehicle options:
–Automatic gearbox
–LPG
–Climate control
–Control and Communications Unit (cannot support fault finding with the tool)
–Automatic parking brake
–Driving School Unit (cannot support fault finding with the tool)
–Discharge bulbs
–Parking assistance
WARNING
A computer connected to the multiplex network but not registered in the computers containing the multiplex
network configuration will not be checked in the multiplex network test.
Adjust the configuration by declaring any missing computers as present in the UCH or airbag computer or both.
Relaunch the multiplex network test after modifying the configuration.

MULTIPLEXING
Diagnostics - Dealing with faults
88B
88B-8
FAULTY COMPUTER
NOTES–Make sure the computers installed in the vehicle are the correct type and are
compatible with Mégane II.
–Check the power supply to 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: Protection and Switching Unit, air conditioning control panel, radio, Control and
Communications Unit.
–+ After ignition: Injection, ABS, airbag, Electric Power Assisted Steering, Automatic transmission, LPG,
Steering lock, Roof control unit, Driving school unit, Automatic parking brake, Parking assistance.
–+ After ignition + dipped headlights: Xenon bulbs.
WARNING
Dialogue with the Xenon bulbs is only possible with + after ignition and the dipped headlights on.
–Switch to computer diagnostics mode.
Test of communication with computers.
⇒No communication from computers to diagnostic tool: see Fault Finding Chart 1
No communication with the computer or computers not communicating with the
diagnostic tool.
Check the connections to the computers and for no open circuit. Repair if necessary.
⇒Computers that only produce partial information when identified:
Check in the Workshop Repair Manual or Global Vehicle Base to see that the computer
really is compatible with Scénic II.
Make sure the CLIP diagnostic tool update is recent enough to handle Scénic II faults.
If after these tests no irregularity or open or short circuit has been detected, contact your Techline.
AFTER REPAIRCarry out a new multiplex network test with the diagnostic tool.
Clear the stored faults on all the computers connected to the network.
Deal with any other possible faults.

MULTIPLEXING
Diagnostics - Dealing with faults
88B
88B-10
MULTIPLEX NETWORK OUT OF ORDER
Help finding network short circuits
NOTESGet a copy of the multiplex network wiring diagram for the vehicle and the diagnostic
socket diagram.
In the event of a short-circuit to + battery, leave the battery connected.
The test procedure involves disconnecting the various network components in sequence to pinpoint the faulty
one.
Check the condition of the connectors.
Check the condition of the multiplex network wires (CAN H - CAN L).
Repair the damaged components.
Systematically repeat the multiplex network test after each operation to see if the fault has been resolved. If
the fault is still shown as present, continue disconnecting the connectors and computers one by one.
Input Output
Connector Can H Can L Connector Can H Can L
Protection and Switching Unit Siemens PEH blue 10 8 PEH blue 11/12 7/9
K4J injection S 3000 C 2AN A black A4 A3
K4M - F4R injection S 3000 C 2AN A black A4 A3 2AN B brown K4 K3
K9K injection LVCR 2AN A black A4 A3
F9Q injection EDC 16 C Black A4 A3
Automatic transmission DP0 Black 38 39
ABS - ESP Black 35 14
ABS Black 26 15
Electric power-assisted steering TRW Black 7 5 Black 6
4
Airbag Black 11 10
Climate control Black 7 1
Steering lock Black 3 6
UCH PE 2 black 6 16 10/8 20/18
Instrument panelGrey
30 29 Red 2 3
Driving school unitBlack
A3 B3
Central communications unit Green 6 7 Grey 3 4
Automatic parking brake Grey A3 A2
R 2 Grey 2 3
R 369White
12 13
OBD (On Board Diagnostic)Black
614
If the fault is not visible, contact your Techline.
AFTER REPAIRCarry out a new multiplex network test with the diagnostic tool.
Clear the stored faults on all the computers connected to the network.
Deal with any other possible faults.

MULTIPLEXING
Fault finding - Fault finding chart
88B
88B-13
CHART 3Configuration chart display
NOTESFault finding chart 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.
The RENAULT loads the configuration screen directly under the following conditions:
●MULTIPLEX NETWORK tab
–Inconsistent Network version numbers entered into the two computers that store the multiplex network
configuration.
–Inconsistent list of computers entered into the computers that store the multiplex network configuration.
–Wrong network version number entered into at least one of the two computers that store the multiplex
network configuration.
–One of the two computers that store the network version is blank (case of replaced airbag or UCH
computer).
●The COMPUTERS THAT CAN SUPPORT FAULT FINDING tab (see screen below)
–Inconsistent diagram numbers entered into the two computers that store the configuration.
–Inconsistency in the list of diagnosable computers entered into the two computers that store the list of
diagnosable computers.
–Inconsistency between the list of computers entered and the computers actually detected on the vehicle.

MULTIPLEXING
Diagnostics - Repair assistance
88B
88B-14
Diagnostics - Repair assistance
CHANGES IN SCENIC II DIAGNOSTICS
●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 properly to the tool. This makes it easier to pinpoint the origin of the failure.
The algorithm for help with locating faults is intended for dealing with electrical faults present solely in CAN; 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
nor with the diagnostic tool. At this point, the network test is out of order.
The CLIP tool can identify several types of faults by taking electrical measurements on the CAN H and CAN L
multiplex network. It can detect a CAN L / CAN H short circuit, a CAN L / + 12 V short circuit, a CAN H / + 12 V short
circuit, and a CAN H / earth short circuit.
Then, by disconnecting the connectors and computers in the order described under the "Help with detecting
segments - computers" heading, the actual or possible segment causing the multiplex network fault can be
identified.
●Disconnecting connectors and computers:
⇒ Help with locating network faults screen
In keeping with the diagnostic tool algorithm and based on the results obtained as it unfolds, the order for
disconnecting connectors and computers recommended by the diagnostic tool will probably be as follows:
Injection, ABS, Protection and Switching Unit, automatic transmission, LPG, steering lock, electric power-
assisted steering, instrument panel, UCH, heating and ventilation system, Control and Communications
Unit, R369 Union, Driving School Unit, airbag, R2 Union, automatic parking brake.
NOTE:
The tool sometimes requests that computers not present in the vehicle concerned be disconnected; in this case,
make sure that the computer in question is not installed, and confirm as though the component concerned had been
disconnected and reconnected and continue the test.
Network physical measurements screen
With the second screen, the operator can check the status of the multiplex network after each disconnection /
reconnection procedure involving the selected connector or computer. This enables the operator to check the status
of the multiplex network after disconnecting each component.