ignition RENAULT SCENIC 2008 J84 / 2.G Engine And Peripherals - Starting Charging Workshop Manual

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16A
Scénic II ph 2
•Battery
The principal purpose of the battery is to provide the powerful current briefly required by the starter motor to start the
engine. For optimum starting, the current supplied by the battery must be sent to the starter motor with minimum
loss. To achieve this, the electrical connections (wires, terminals, connectors, etc.) must be in good condition.
When the engine is not running, the battery must feed the accessories that operate constantly, even with the ignition
switched off, such as the alarm, radio codes, computers, etc.
•Starter
This turns the engine over to make it start, and requires a very powerful electric current, which the battery must be
able to supply.
•Alternator
The alternator only operates when the engine is running. Its function is to recharge the battery, and at the same time
to supply the electrical power required to operate all the electrical accessories on the vehicle.
The alternator on Mégane II phase 2 is a controlled alternator. The UPC* controls the regulation via a serial
connection.
•Engine Compartment Connection Unit or Protection and Switching Unit
The UPC* is connected to the alternator by a serial connection. The UPC* intelligently manages the alternator
regulation voltage according to the engine phase, the battery charge, and the temperature.
•The UCH
The UCH* interprets the starting request and analyses if the starting conditions are satisfied, in order to transmit the
request to the UPC*.
*UPC: Engine Compartment Connection Unit or Protection and Switching Unit
*UCH: Passenger Compartment Central Unit
STARTING - CHARGING
Fault finding – Role of components

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16A
Scénic II ph 2
The function of the charging circuit is to:
•Ensure that electrical energy is supplied to the vehicle whilst respecting the dynamic performance constraints of
the engine and transmission assembly: the alternator resisting torques and the torque gradients measured must
be managed.
•To control alternator loading and load shedding during engine management authorisation or variation of the
electrical load.
•To ensure the quality of the on board network voltage in terms of the voltage level and variation (voltage gradient
management).
•To optimise the battery charge by applying a voltage to its terminals correlating to its initial charge status (in sleep
mode) and to its internal temperature.
•To inform the engine management about the mechanical power taken from the accessories pulley, the alternator
charge rate and the rotor excitation current value.
•To run fault finding on the charging circuit: "Battery" warning light display.
The function of the starting circuit is to:
•start the vehicle when there is a starting request from the ignition key.
STARTING - CHARGING
Fault finding – Features

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STARTING - CHARGING
Fault finding – Fault finding charts16A
Scénic II ph 2
ALP 1
CONTINUED 1
With the ignition switched off, measure the voltage between the battery earth and the starter control terminal.
Voltage value?
While activating the starter, measure the voltage
between the battery earth and the starter control
terminal.Disconnect the starter control terminal wire and
measure the voltage on the wire of connection 1A
again.
Voltage value? Voltage value?
Replace the starter (see MR 370,
Mechanical, 16A, Starting -
Charging, Starter: Removal -
Refitting).Replace the starter (see MR 370,
Mechanical, 16A, Starting - Charging,
Starter: Removal - Refitting).
Disconnect connector MM on component 1337 and measure the voltage on connection 1A.
Voltage value?
Repair the damaged wires and terminals of
connection 1A. If the connection is faulty and
there is a repair procedure (see Technical Note
6015A, Electrical wiring repair, Wiring:
Precautions for repair), repair the wiring,
otherwise replace it.Run complete fault finding on component 1337 (see
87G, Engine compartment connection unit).
A
< 1 VBetween 1 V and 10 V≥ 10 V
≥ 10 V< 10 V
C
≥ 10 V< 10 V
< 10 V≥ 10 V

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STARTING - CHARGING
Fault finding – Fault finding charts16A
Scénic II ph 2
ALP 1
CONTINUED 3
Check the starting request from component
645 using ET062 UCH request to UPC
(see 87G, Passenger compartment
connection unit, Fault finding -
Interpretation of statuses).
Is component 1337 receiving the request?Check for + 12 V after ignition on connection
AP10 of connector CN of component 1337.
Is there 12 V?
Check for 12 V on connection 1A of
connector MM during a request.
Is there 12 V?Supply fault on connection
AP10 of connector CN of
component 1337.
Continuity fault on connection 1A between
components 1337 and 163. If the
connection is faulty and there is a repair
procedure (see Technical Note 6015A,
Electrical wiring repair, Wiring:
Precautions for repair), repair the wiring,
otherwise replace it.Replace component 1337
C
YES
NO
D
YESNO
YESNO

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STARTING - CHARGING
Fault finding – Fault finding charts16A
Scénic II ph 2
ALP 1
CONTINUED 4
Check the request from component 104
using ET239 Ignition switch position
(see 87B Passenger compartment
connection unit, Fault finding -
Interpretation of statuses).
Is component 645 receiving the request?Is the CAN network OK?
Presence of effective + after ignition feed
Check the voltage on connection D at the
input of fuse for component 260 when
starting is requested.
Is there 12 V?Run fault finding on the CAN network
Continuity fault on connection DP between components 260
and 645. If the connection is faulty and there is a repair
procedure (see Technical Note 6015A, Electrical wiring
repair, Wiring: Precautions for repair), repair the wiring,
otherwise replace it.Replace component 645
Check the voltage on connection D of
component 104 when starting is requested.
Is there 12 V?Replace component 104
Continuity fault on connection D between components 104 and 260. If there is a repair
method (see Technical Note 6015A, Repairing electrical wiring, Wiring: Precautions for
repair) repair the wiring, otherwise replace it.
D
YES
NOYES
NO
NOYES
NO
YES

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STARTING - CHARGING
Fault finding – Tests16A
Scénic II ph 2
TEST 2 Test the condition of the power fuse and the cause of its fault
NOTESCheck that the engine is not blocked.
With the ignition off, measure the voltage between the negative battery terminal
and the power fuse output
Is the voltage greater than or equal to 10V?
The power fuse is correct The power fuse is faulty
With the battery disconnected, measure the resistance
between the negative battery terminal and the power fuse
output
Is the resistance
≥ 10 ΩΩ Ω Ω
?
Disconnect the alternator + terminal, then measure
the resistance between the negative battery terminal
and the power fuse outputPossible external causes:
use of a "starter charger", excessively long use of
starter (e.g.: activating the starter with the gear
engaged to move the vehicle) etc.
Is the resistance
≥ 10 Ω?
Replace the alternator (see MR 370, Mechanical, 16A, Starting - Charging,
Alternator: Removal - Refitting).
Check the wiring connecting the alternator and the
starter to the battery + terminal (see TEST 3 Wiring
check).
Is it in good condition?
YESNO
NOYES
D
NO
YES
CNO
A
YES
B