sensor RENAULT SCENIC 2003 J84 / 2.G General Information

FAULT FINDING INTRODUCTION
General method
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101EFAULT FINDING INTRODUCTION
General method
The Scénic II is a multiplexed vehicle equipped with a communications network operating at a speed of
500 kBauds.
This change has allowed a new optimisation of the electronic layout of the vehicle in two ways:
●Distribution of vehicle functions: the main computers present on the multiplex network manage several
functions (example: UCH: access - vehicle protection - lighting - wipers - passenger compartment heating - tyre
pressure monitor).
●Elimination of redundant sensors: the "steering wheel angle" signal used by the electronic stability program
is produced by the electric power assisted steering which then transmits it to the multiplex network. So the
steering wheel angle sensor used by the electronic stability program does not exist.
This change has also allowed fault finding on computers present on the multiplex network to be performed by the
main communication network of the vehicle (multiplex network) instead of a cable network dedicated to fault
finding (K / L lines).Warning:

Scénic II diagnostics can only be done with the CLIP fault-finding tool equipped with the vehicle diagnostic
probe (part no.: Elé. 1674).
Note:
The multiplex network of the vehicle is the main functional communication network of the vehicle. But
certain optional functions are still performed by track wires.
IMPORTANT
However, the Scénic II still uses two different physical fault finding media:
●The multiplex network: which allows fault finding of the following computers: instrument panel, electric
power assisted steering, airbag, automatic air conditioning, UCH, anti-lock braking system - electronic
stability program, protection and switching unit, injection.
●K / L lines diagnostic network: for fault finding on the following computers: automatic transmission,
automatic parking brake, discharge bulbs and parking assistance.
Some other computers, while connected to the vehicle's multiplex network, have their own "self-test" function:
central communications unit (Carminat), driving school unit or that cannot be diagnosed with the tool: steering
lock (governed by the UCH).
IMPORTANT
Computer supply for the fault finding procedure:
To run fault finding on the vehicle computers, proceed as follows:
●Vehicle card in card reader
●Press and hold start button (longer than 5 seconds) with start-up conditions not fulfilled,
●Connect the diagnostic tool and perform the required operations.

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Innovations to the Scénic II:
The innovations in Scénic II fall into three categories:
1 - Functional innovations:
The main functional innovations on the vehicle are as follows:
FUNCTIONAL
INNOVATIONS This section describes the new services present on the vehicle and their integration on
the vehicle.
ARCHITECTURAL
INNOVATIONS This section describes the distribution of the main functions and the new computers
fitted to the vehicle.
FAULT FINDING
INNOVATIONS This section describes the fault finding changes implemented on the Scénic II in order
to:
●Allow fault finding on the multiplex network of the vehicle (vehicle to diagnostic tool
connection sensor).
●Develop and complement multiplex network fault finding functions (physical
measurements of the type of fault, fault finding assistance etc.).
●Mask the diversity and complexity of vehicle functions: fault finding by function, multi-
computers, etc.
KEYLESS VEHICLE
(access, protection -
de-protection and
hands-free starting)This function is provided by the following computers:
●UCH: responsible for access and vehicle protection (immobiliser).
●Steering lock: participates in vehicle protection (electromechanical locking of the
steering column).
●Injection: responsible for vehicle protection (immobiliser) and control of the starter
motor.
●Protection and Switching Unit: responsible for the power supplied to the starter motor
at the request of the UCH, and for injection management.
ELECTRONIC
STABILITY
PROGRAMThis function is provided by the following computers:
●Anti-lock braking system - electronic stability program: responsible for the trajectory
analysis function by means of the speed sensors, the yaw sensor, the transverse
acceleration sensor and the steering wheel angle (driver's intention: signal sent by
the electric power assisted steering).
●Injection: management of engine torque in order to correct the trajectory at the
request of the electronic stability program or automatic transmission.
●Automatic transmission: translation (shared with the injection computer) of driver's
intention, sends torque requests to the injection computer.

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LIGHTING - XENON
BULBThis function is provided by the following computers:
●UCH: translation of driver's intention, management of the lighting stalk, the direction
indicators and the rear fog lights.
●Switching Protection Unit: responsible for the power needed for lighting, the side
lights, the main beam headlights and the front fog lights.
●XENON bulb: responsible for management and correction of the dipped headlights.
IMPORTANT
The "discharge bulb" function in the Scénic II involves the following components:
●Two body-height sensors in the front and rear wheel arches on the left side.
The built-in front height sensor as well as the computer that manages
this feature.
●Two units that adjust / produce high-voltage lighting installed in the vehicle's
headlight units.
MULTIMEDIAThis function is provided by the following computers:
●Central Communication Unit (Carminat): responsible for the function.
●Navigation display: displays information relating to navigation.
IMPORTANT
This function may also be provided by the radio display, depending on the type of
navigation (basic - top of the range).
TYRE PRESSURE
MONITORThis function is provided by the following computers:
●UCH: responsible for the function, it also houses the receiver for tyre pressure
signals.
●Instrument panel: displays information relating to the tyre pressure monitor.
Note:
The tyre pressure is monitored by specific valves fitted with tyre pressure sensors.
AUTOMATIC
PARKING BRAKEThis function is provided by the following computers:●Automatic parking brake: manages the function and consists of the computer,
vehicle position sensor (gyroscope) as well as the mechanical cable locking /
unlocking system.
●Instrument panel: displays information about the automatic parking brake feature.
PARKING
ASSISTANCEThis function is provided by the following computers:●Parking assistance: manages the function with the instrument panel beeper
providing the user interface.

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3 - Fault finding innovations:
Development of the electronic and functional design of the Mégane has necessitated changes in the fault finding
processing used. The main fault finding changes are as follows:
●Vehicle to fault-finding tool connection sensor: this equipment is required for communication with the
computers attached to the vehicle's main communications network: the multiplex network. It also enables
communication with the computers diagnosed with the K / L lines.
●New fault-finding tool navigation interface:
The navigation interface of the fault-finding tool has changed to accommodate the Scénic II. Note in particular
the following changes:
–Vehicle identification by entering the VIN:
This can be done manually, or automatically by querying the
vehicle. It also gives the After-Sales type, and the engine and gearbox type.
–Distinction between the fault finding and repair menus:
The fault finding menu incorporates all the
functionalities associated with analysis of an electrical or electronic fault (processing of faults, conformity
checking, actuator commands and processing by customer complaint) whereas the repair menu allows
performance of all the operations associated with replacement of a component and/or modification of the
diagnostic system configuration (configuration read operations, configuration, programming, specific
commands etc.).
●New electronic layout integrity test: As correct operation of the vehicle is dependent on the integrity of the
multiplex network (main functional communication network) and of the cabled electronic systems, the multiplex
network test has changed, becoming the vehicle electronic layout integrity test. The changes are as follows:
–Multiplex network test:
This test remains similar to that already used for RENAULT multiplex vehicles. But it
also incorporates a read of the number of faults from the multiplex computers, physical measurements of the
types of multiplex network faults (open circuit, short circuit to earth, short circuit to the +ve of the faulty rings)
and an assisted help procedure for detecting the defective computer or ring (in the event of total paralysis of
the network). IMPORTANT:
The airbag harness tests and the various physical measurement tests must always be carried out using the
existing diagnostic tool leads and modules.
IMPORTANT:
Entering the VIN, which associated with entering the repair order, can generate the Computer
Diagnostic Sheet electronically.