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
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.
