ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Introduction87G
87G - 3V7 MR-372-J84-87G050$055.mif
UPC
Vdiag No.: 48, 4C
3. REMINDER
PROCEDURE
To run fault finding on the vehicle's computers, switch on the ignition in fault finding mode (forced + after ignition
feed). Run the self-test procedure for the UPC internal relays and fuses using AC016 Electrical supply circuit
test.
Depending on the type of vehicle equipment, proceed as follows:
To cut off the + after ignition feed, proceed as follows:
Faults
Faults are declared as either present or stored (depending on whether they appeared in a certain context and have
disappeared since, or whether they remain present but have not been diagnosed within the current context).
The present or stored status of faults should be taken into consideration when the diagnostic tool is used following
the + after ignition supply being switched on (without operating the system components).
For a present fault, apply the procedure described in the Interpretation of faults section.
For a stored fault, note the faults displayed and apply the instructions in the Notes section.
If the fault is confirmed when the instructions in the Notes section are applied, the fault is present. Deal with the fault
If the fault is not confirmed, check:
–the electrical lines which correspond to the fault,
–the connectors on these lines (corrosion, bent pins, etc.),
–the resistance of the component detected as faulty,
–the condition of the wires (melted or split insulation, wear). WARNING
Switch off all unnecessary consumers:
–Radio navigation system.
–Switch the passenger compartment ventilation speed to 0.
–Switch off the interior lights (forced off).
With the vehicle card in the card reader, press and hold the start button (+ 5 seconds) outside starting conditions,
connect the diagnostic tool and carry out the required operations.
Press the start button twice briefly (less than 3 seconds); check that the + after ignition feed has cut (computer
indicator lights on the instrument panel go out).
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 - Fault finding charts87G
87G-91V7 MR-372-J84-87G050$880.mif
UPC
Vdiag No.: 48, 4C
ALP3No backlighting of the various functions in the passenger
compartment
NOTESMake sure that the side lights are working; if not, refer to the procedure for command
AC003 Side lights.
Use Wiring Diagrams Technical Note for Mégane II or Scénic II.
Check the condition and connection of the defective functions.
If the connector is faulty and there is a repair procedure (see Technical Note 6015A, Electrical wiring repair,
Wiring: Precautions for repair), repair the connector, otherwise replace the connector.
Check for earth on the defective function(s).
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.
With the side lights on, check for 12 V on the defective function(s).
If correct, replace the defective component.
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.
Check the insulation, continuity, and the absence of interference resistance between the defective function
and the Protection and Switching Unit:
Right-hand headlight component code 226, rear right-hand
lights component code 172, right-hand and left-hand heated
seat control component codes 1513 and 1514, parking distance
control switch component code 1540, cruise control/speed
limiter control component code 1081, ESP on/off button
component code 1106, gear lever display component code
1129, hard roof switch component code 1482, simultaneous
window control component code 854, LPG or petrol selector
switch component code 1003, right-hand number plate light
component code 166.LPDConnector CN of the
Protection and Switching
Unit, component code
1337.
Left-hand rear light component code 173, left-hand headlight
component code 227, child safety switch component code 135,
CD changer component code 1272, radio component code
261, multifunction display component code 653, headlight
adjustment rheostat switch component code 1390, warning/door
locking switch component code 1391, first cigarette lighter
component code 101.LPGConnector CN of the
Protection and Switching
Unit, component code
1337.
If the connections are faulty and there is a repair procedure (see Technical Note 6015A, Electrical wiring repair,
Wiring: Precautions for repair), repair the wiring, otherwise replace it.
If the fault is still present, contact the Techline.
AFTER REPAIRCheck that no fault is present.
USM_V48_ALP3 /USM_V4C_ALP3
