charging RENAULT SCENIC 2008 J84 / 2.G Engine Compartment Connection Unit Workshop Manual

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - System operation87G
87G-8V7 MR-372-J84-87G050$110.mif
UPC
Vdiag No.: 48, 4CENGINE COMPARTMENT CONNECTION UNIT
Fault finding - System operation
General operation
The Protection and Switching Unit is involved in the following functions:
–Access - Safety.
–Air conditioning.
–Lighting.
–Wipers.
–Charging circuit.
–Oil pressure detection.
–Electric power distribution.
1 - Electric power distribution
The main function of the Protection and Switching Unit is to switch and distribute the power supply to the vehicle's
systems, actuators or computers.
Part of this function is handled within the unit, but it is not electronically controlled by the computer.
+ 12 V battery feed
The Protection and Switching Unit receives energy from the battery via the Busbar and MM connectors (tracks 6 and
4) and redistributes the + 12 V feed.
+ 12 V after ignition
The UCH sends the Protection and Switching Unit the + 12 V after ignition feed request via the multiplex network.
When the Protection and Switching Unit receives this request, it actuates the after ignition relay unconditionally. The
signal is distributed to the sensors, actuators and computers.
2 - Charge circuit
One of the main functions of the Protection and Switching Unit is managing the charge circuit.
Purpose and components:
The main function of the charging circuit is to produce and distribute the electrical energy required to operate the
various electrical consumers on the vehicle (computers, lights, etc.).
It is also used to start the engine.
The main components are a battery, an alternator and a starter motor.
MR-372-J84-87G050$110.mif

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - System operation87G
87G-10V7 MR-372-J84-87G050$110.mif
UPC
Vdiag No.: 48, 4C
Only on vehicles with M9R injection:
The injection computer also acts on the alternator regulation voltage. The injection computer sends the maximum
authorised power delivered by the engine, to the UPC computer via the multiplex network. If the power from the engine
is less than the power consumed by the alternator, the UPC computer will reduce the alternator voltage.
For vehicles with any injection type except M9R:
The UPC sends the alternator charge to the injection to regulate the idling speed.
c) 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.
The computer receives the starter activation request via the multiplex network from:
–injection,
–UCH,
–the automatic gearbox.
(see ET010 Starting conditions met)
The computer controls the starter relay.
In the event of a fault with the starter, refer to section 16A, Starting - Charging, Starter.
3 - Keyless vehicle
Under the keyless vehicle function, the Protection and Switching Unit is involved in the starting sub-function. The
computer:
–receives the supply request from the passenger compartment starter via the multiplex network, as well as the clutch
pedal position,
–controls the starter relay,
–inhibits or cuts out this relay control according to a signal prohibiting starting which is sent by the injection computer
or gearbox via the multiplex network (see 87B, Passenger compartment connection unit).
4 - Air conditioning
For the operation of the air conditioning and the role of the Protection and Switching Unit in the control of this
function (see 62A, Air conditioning).
Cold loop:
The computer receives the compressor switch-on request from the injection via the multiplex network.
The computer controls the compressor clutch engagement relay.
Heating:
The computer manages the alternator charge and sends back the signal over the multiplex network.
The computer also controls the rear screen de-icing.

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults87G
87G-19V7 MR-372-J84-87G050$330.mif
UPC
Vdiag No.: 48, 4C
DF007
CONTINUED 2
Perform three successive acquisitions at intervals of 10 to 15 seconds.
Check that the signal resembles the image above.
If so:
Replace the alternator (see MR 364 or 370 Mechanical, 16A, Starting - Charging, Alternator: Removal -
Refitting).
Otherwise:
Contact Techline.
MULTIMETER
UNIVERSAL SCOPE
TIME BASE
2 ms/div
TRIGGER
AUTO
RANGE
2.5 V/div
AFTER REPAIRErase the faults from the computer memory, switch the + after ignition supply off and
back on again, and run another check using the diagnostic tool after 10 minutes
with the engine running.

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults87G
87G-21V7 MR-372-J84-87G050$330.mif
UPC
Vdiag No.: 48, 4C
DF007
CONTINUED 4
CC
NOTESNone.
Check the connection and condition of the alternator connector, component code 103.
If the connector is faulty and if there is a repair procedure (see Technical Note 6015A, Electrical wiring repair,
Wiring: Precautions for repair), repair the connector, otherwise replace the connector.
Check the connection and condition of connector MT1 for the Protection and Switching Unit, component code
1337.
If the connector is faulty and if there is a repair procedure (see Technical Note 6015A, Electrical wiring repair,
Wiring: Precautions for repair), repair the connector, otherwise replace the connector.
Disconnect the UPC-Alternator connection for the alternator and the Protection and Switching Unit.
Ensure that the UPC-Alternator connection is insulated in relation to the + 12V supply and the earth:
–2N between components 1337 and 103.
If the connection is faulty and if there is a repair procedure (see Technical Note 6015A, Electrical wiring repair,
Wiring: Precautions for repair), repair the wiring otherwise replace the wiring.
If the fault is still present, disconnect the connector from the Protection and Switching Unit.
In + after ignition feed, measure the voltage of the connector MT1 for the Protection and Switching Unit on
connection code 2N.
If the voltage is less than 3V or greater than 9V:
Replace the Protection and Switching Unit (see Replacement of components).
If the voltage is between 3V and 9V:
Replace the alternator (see MR 364 or MR 370 Mechanical, 16A, Starting - Charging, Alternator: Removal -
Refitting).
AFTER REPAIRErase the faults from the computer memory, switch the + after ignition supply off and
back on again and run another check using the diagnostic tool.

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults87G
87G-24V7 MR-372-J84-87G050$330.mif
UPC
Vdiag No.: 48, 4C
DF012
PRESENT
OR
STOREDALTERNATOR
1.DEF: Alternator mechanical or electrical fault
NOTESConditions for applying the fault finding procedure to present faults:
The fault is declared present after the engine has been running for at least 1 minute.
Special note:
The fault illuminates the Battery and STOP warning lights on the instrument panel.
Use Wiring Diagrams Technical Note for Mégane II or Scénic II.
1.DEF
NOTESNone.
Check the fitting, condition and tension of the accessories drive belt.
Visually check that the alternator is not clogged.
Clean out the alternator cooling vents using an air gun.
Check the wiring, the connections and the earths (see Test no. 1 Wiring test).
If the connection is faulty and if there is a repair procedure (see Technical Note 6015A, Electrical wiring repair,
Wiring: Precautions for repair), repair the wiring otherwise replace the wiring.
Run command AC014 Alternator regulation (see Interpretation of commands).
With the bonnet closed, start the engine.
Leave the engine to run for 2 minutes at idle speed.
If the fault is still present, replace the alternator (see MR 364 or MR 370 Mechanical, 16A, Starting - Charging,
Alternator: Removal - Refitting).
AFTER REPAIRErase the faults from the computer memory, switch the + after ignition supply off and
back on again and run another check using the diagnostic tool.
USM_V48_DF012/USM_V4C_DF012

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of statuses87G
87G-68V7 MR-372-J84-87G050$550.mif
UPC
Vdiag No.: 48, 4C
ET010
STARTING CONDITIONS MET
NOTESSpecial notes:
Apply the checks if the status is at STATUS 1, STATUS 2 or STATUS 3 or YES, with
the ignition on.
STATUS 1
The UCH is preventing the Protection and Switching Unit from activating the starter.
Run fault finding on this computer (see 87B, Passenger compartment connection unit, UCH Vdiag No.: 44, 48,
4C, 4D, 4F, 50).
STATUS 2
The injection is preventing the Protection and Switching Unit from running the starter.
Run fault finding on this computer (see 13B, Diesel injection and 17B, Petrol injection).
STATUS 3
The automatic gearbox computer is preventing the Protection and Switching Unit from running the starter.
Make sure that the selector lever is in position P or N.
Run fault finding on this computer (see 23A, Automatic gearbox).
YES
If the conditions are met and the starter does not operate, see 16A, Starting - Charging, Starter.
If the fault is still present, contact your Techline.
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_ET010 /USM_V4C_ET010

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of statuses87G
87G-69V7 MR-372-J84-87G050$550.mif
UPC
Vdiag No.: 48, 4C
ET023
ALTERNATOR THERMAL FAULT
NOTESSpecial notes:
Apply the checks if the status is PRESENT with the engine running.
Switch off the engine.
Check the general condition of the alternator:
Make sure that there are no foreign bodies that could impair the alternator cooling.
Clean the alternator if necessary.
With the engine stopped, let the alternator cool down with the bonnet open for at least 1 hour.
Start the engine with the bonnet closed.
Switch on the main beam headlights and the electrical heated rear screen.
If the status becomes PRESENT again, replace the alternator (see MR 364 or MR 370 Mechanical, 16A,
Starting - Charging, Alternator: Removal - Refitting).
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_ET023 /USM_V4C_ET023

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of parameters87G
87G-72V7 MR-372-J84-87G050$660.mif
UPC
Vdiag No.: 48, 4CENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of parameters
PR004
BATTERY VOLTAGE
NOTESSpecial notes:
Check that all of the electrical consumers are switched off:
–Passenger compartment blower unit stopped.
–Radio off (and Radio navigation system if fitted to the vehicle).
–Interior lights off.
If fault DF013 Voltage regulation is not present (or stored):
With the engine stopped and no electrical consumers operating for 5 minutes.
Check the battery, see TEST3 Battery status test.
If fault DF013 Voltage regulation is present:
With the engine running at idle speed, and electrical consumers activated:
–Dipped headlights and side lights.
–Electric heated rear screen.
–Passenger compartment blower unit in maximum position.
Check the consistency between the battery voltage measurement from the multimeter and the value of PR004
Battery voltage.
If the difference is greater than 1 V check the conformity of the Protection and Switching Unit supply circuit and
the charging circuit wiring TEST2 Wiring test.
Repair if necessary, otherwise replace the Protection and Switching Unit (see Replacement of components).
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_PR004 /USM_V4C_PR004
MR-372-J84-87G050$660.mif

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of parameters87G
87G-73V7 MR-372-J84-87G050$660.mif
UPC
Vdiag No.: 48, 4C
PR008
BATTERY VOLTAGE AFTER REST
NOTESSpecial notes:
This value can only be interpreted after the engine and electrical consumers have been
stopped for at least 8 hours.
Apply if the Charge battery message is displayed on the instrument panel.
Recharge the battery (see Technical Note 6512A, Charging).
Check the battery (see 80A, Battery).
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_PR008 /USM_V4C_PR008

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of parameters87G
87G-74V7 MR-372-J84-87G050$660.mif
UPC
Vdiag No.: 48, 4C
PR010
ALTERNATOR CHARGE
NOTESIf fault DF007 UPC-alternator connection is declared present, deal with this fault first.
Start the engine and let it idle for 5 minutes.
Check that the fan units are not running.
Without any electrical consumers switched on, check the value of PR010 Alternator charge.
PR010 decreases and is < 50 % after a few minutes.
"YES"
No interfering consumer is disturbing vehicle operation.
–Switch on the electric heated rear screen and the main beam headlights.
–Wait 20 seconds and then check that PR010 Alternator charge has increased but
remains less than 90%.
If PR010 Alternator charge remains stuck at 99.6%, replace the alternator (see MR 364
or MR 370 Mechanical, 16A, Starting - Charging, Alternator: Removal - Refitting).
PR010 remains > 50% after 20 minutes.
–See 16A, Starting - Charging, Alternator output.
"NO"
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_PR010 /USM_V4C_PR010