2008 RENAULT SCENIC air condition

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Introduction87G
87G - 4V7 MR-372-J84-87G050$055.mif
UPC
Vdiag No.: 48, 4C
Conformity check
The aim of the conformity check is to check data that does not produce a fault on the diagnostic tool because the
data is inconsistent. Therefore, this stage is used to:
–carry out fault finding on faults that do not have a fault display, and which may correspond to a customer
complaint.
–check that the system is operating correctly and that there is no risk of a fault recurring after repairs.
This section gives the fault finding procedures for statuses and parameters and the conditions for checking them.
If a status is not behaving normally or a parameter is outside the permitted tolerance values, consult the
corresponding fault finding page.
Customer complaints - Fault finding chart
If the test with the diagnostic tool is OK but the customer complaint is still present, the fault should be dealt with by
Customer complaints.
A summary of the overall procedure to follow is provided on the following page in
the form of a flow chart.

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 - System operation87G
87G-12V7 MR-372-J84-87G050$110.mif
UPC
Vdiag No.: 48, 4C
9 - Injection
The Protection and Switching Unit is involved in injection operation, relating to supplying the computer and its
sensors.
Supply malfunctions may lead to engine management customer complaints (rough idle, etc.).
10 - Fuse fault finding
The Protection and Switching Unit can detect the condition of its fuses and indicate faults using:
DF014 LEFT-HAND SIDE LIGHT CIRCUIT.
DF015 RIGHT-HAND SIDE LIGHT CIRCUIT.
DF016 LEFT-HAND DIPPED HEADLIGHT CIRCUIT.
DF017 RIGHT-HAND DIPPED HEADLIGHT CIRCUIT.
DF018 LEFT-HAND MAIN BEAM HEADLIGHT CIRCUIT.
DF019 RIGHT-HAND MAIN BEAM HEADLIGHT CIRCUIT.
DF020 FRONT FOG LIGHT CIRCUIT.
DF021 REVERSING LIGHT(S) CIRCUIT.
DF022 REAR SCREEN DE-ICER CIRCUIT.
DF023 FRONT WINDSCREEN WIPER CIRCUIT.
DF024 GAS COMPUTER SUPPLY.
DF025 AIRBAG/ELECTRIC POWER-ASSISTED STEERING SUPPLY.
DF026 AUTOMATIC TRANSMISSION SUPPLY.
DF029 STEERING COLUMN LOC/ENGINE MANAGEMENT SUPPLY.
DF030 AIR CONDITIONING COMPRESSOR SUPPLY CIRCUIT.
DF031 HEADLIGHT WASHERS SUPPLY CIRCUIT.
DF032 + 12 V RELAY SUPPLY CIRCUIT.
DF036 STEERING COLUMN LOCK SUPPLY CIRCUIT.
To carry out fault finding on the fuses, run command AC016 Test electrical supply circuits.
If a fuse is faulty, the associated fault becomes STORED.
Once the fuse has been replaced or the repair completed, run command AC016 Test electrical supply circuits
again to clear the fault.
Protection and Switching Unit Version
There are 4 Protection and Switching Unit versions:
–N1: vehicle with a 340 W fan assembly.
–N2: vehicle with a 460 W fan assembly.
–N3: vehicle with a 550 W fan assembly (external relay).
–N4: vehicle with 340 W, 460 W or 550 W fan assemblies + automatic transmission and/or LPG and/or with
headlight washers.

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults87G
87G-16V7 MR-372-J84-87G050$330.mif
UPC
Vdiag No.: 48, 4CENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults
DF006
PRESENT
OR
STOREDCOMPUTER
1.DEF: Internal electrical fault
NOTESConditions for applying the fault finding procedure to stored faults
The fault is declared present after the ignition is switched off and back on.
If the fault is present, contact Techline.
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_DF006/USM_V4C_DF006
MR-372-J84-87G050$330.mif

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults87G
87G-17V7 MR-372-J84-87G050$330.mif
UPC
Vdiag No.: 48, 4C
DF007
PRESENT
OR
STOREDUPC - ALTERNATOR CONNECTION
CO: Open circuit
CC: Short circuit to earth
1.DEF: Communication disrupted
NOTESSpecial notes:
–Check the conformity of the wiring (see Test no. 2 Wiring test).
Repair if necessary.
–The fault illuminates the Battery charge warning light on the instrument panel and
the STOP warning light.
–Conditions for applying the fault finding procedure to stored faults:
The fault is declared present after the engine has been running for 10 minutes.
Use Wiring Diagrams Technical Note for Mégane II or Scénic II.
CO
NOTES+ APC.
Engine stopped.
Disconnect the UPC-Alternator connection for the alternator component code 103.
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.
Measure the voltage on connection 2N between the alternator, component code 103 and the battery earth,
component code 107.
If the voltage is less than 3 V
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.
Check the insulation, continuity and the absence of interference resistance on the following connection:
–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, replace the Protection and Switching Unit (see Replacement of components).
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.
USM_V48_DF007/USM_V4C_DF007

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of faults87G
87G-20V7 MR-372-J84-87G050$330.mif
UPC
Vdiag No.: 48, 4C
DF007
CONTINUED 3
1.DEF
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.
With the engine running, switch on the electrical heated rear screen.
Measure the voltage between the earth of the alternator casing component code 103 and the battery earth
component code 107.
If the difference is over 1 V, check the vehicle earths.
If the fault is still present, contact the Techline.
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-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.