Page 65 of 68

AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - Fault Interpretation
88C - 65
88C
V3 MR-372-J84-88C000$072.mif
AIRBAG ACU4
Vdiag: 04
DF241
CONTINUED
CC.1 - CC.0
NOTESNone.
Lock the computer.
Check the connections of the 22-track connector under the seat. Repair if necessary. Attach the 22-track
(Elé. 1687) test adapter under the seat (point C1).
The CLIP or XRBAG tool absolutely must be used to measure the proper insulation for the type of fault in
cable B.
Is the value obtained correct?
NO
YES
Seat wiring fault.
Replace the wiring between pointsC1 and C3.
Wiring fault between the computer and passenger's seat (C0/C1).
Replace the wiring if necessary.
AFTER REPAIRReconnect the computer and the passenger seat-cushion airbag/lap belt ignition
module, then switch the ignition back on. Clear the computer memory then switch off
the ignition.
Carry out the check again using the diagnostic tool and, if there are no faults, unlock
the computer. When replacing the airbag module, do not forget to reconnect the earth
on the new one.
Destroy the seat airbag module or driver's seat lap belt pretensioner if it has been
replaced (tool Elé. 1287).
ACU4 Vdiag04 J84 1.0
Page 66 of 68

AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - States and parameter summary table88C
88C - 66V3 MR-372-J84-88C000$080.mif
AIRBAG ACU4
Vdiag: 04
AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - States and parameter summary table
ACU4 AIRBAG STATES SUMMARY TABLE:
ACU4 AIRBAG PARAMETERS SUMMARY TABLE:
The trigger line or sensor impedance is 99.9Ω when the component is disconnected or not controlled by the
computer.STATES
TOOLDIAGNOSTIC TOOL HEADINGS
ET010
ET072
ET073
ET074
ET076
ET103
ET105
ET108
ET143
ET144Impact detected
Passenger airbag status indicator light commanded
Computer locked by tool
Fault warning light commanded
Computer to replace
Type of passenger airbag lock
Locked diagnostics power supply out of limits
Passenger airbag lock mode
Passenger airbag(s) locked
Fault present or in memory
PARAMETERS
TOOLDIAGNOSTIC TOOL HEADINGS
PR001
PR002
PR104
PR105
PR106
PR107
PR108
PR109
PR110
PR111
PR112
PR113
PR114
PR115
PR116
PR117
PR118
PR140
PR147Computer supply voltage
Vehicle type
Driver's seat sensor impedance
Line 1 impedance (Driver's seat / lap airbag circuit).
Line 2 impedance (Passenger's seat / lap airbag circuit).
Line 3 impedance (Passenger's front airbag circuit 1).
Line 4 impedance (Passenger's front airbag circuit 2).
Line 5 impedance (Driver's front airbag circuit 1).
Line 6 impedance (Driver's front airbag circuit 2).
Line 7 impedance (Driver's side curtain side airbag circuit).
Line 8 impedance (Passenger's side curtain side airbag circuit).
Line 9 impedance (Driver's front frontal side airbag circuit).
Line 10 impedance (Passenger's front frontal side airbag circuit).
Line 11 impedance (Driver's rear frontal side airbag circuit).
Line 12 impedance (Passenger's rear frontal side airbag circuit).
Line 13 impedance (Front belt pretensioners circuit).
Line 14 impedance (Rear retractors).
Number of memory zone deletions
Airbag lock circuit impedance
ACU4 Vdiag04 J84 1.0
MR-372-J84-88C000$080.mif
Page 67 of 68
AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - Conformity check
88C - 67
88C
V3 MR-372-J84-88C000$090.mif
AIRBAG ACU4
Vdiag: 04
AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - Conformity check
NOTESOnly carry out conformity check after a full check using the diagnostic tool.
Order FunctionParameter or State
Check or Action Display
and notesFault finding
1Diagnostic tool
dialogue- CHART 1Airbag ACU 4
2Computer
conformityParameter PR002 "Vehicle
type"DF001 MEGANE II:48
3Computer
configurationUsing "READ
CONFIGURATION" commandsEnsure that the computer
configuration defined in the
"Current" column
corresponds to the vehicle
equipment.None
4Warning light
operation
Computer
initialisation
check.Ignition switched onWarning light comes on for
3 seconds when the ignition
is switched onNone
ACU4 Vdiag04 J84 1.0
MR-372-J84-88C000$090.mif
Page 68 of 68

AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - Fault finding chart
88C - 68
88C
V3 MR-372-J84-88C000$100.mif
AIRBAG ACU4
Vdiag: 04
AIRBAG - SEAT BELT PRETENSIONERS
Fault finding - Fault finding chart
CHART 1 No communication with the airbag computer
NOTESSpecial note: To perform fault finding on the vehicle computers, switch on the
ignition in fault finding mode (+ after ignition imposed), i.e. proceed as follows:
–Vehicle card in card reader, press on the Start button for more than five
seconds outside of starting conditions.
Ensure that the diagnostic tool is not causing the fault by trying to establish dialogue with a computer on
another vehicle. If the tool is not the problem and communication cannot be established with any other
computer in the same vehicle, check the battery voltage and do the work required to obtain the proper reading
(10.5 V < battery voltage < 16 V).
Check the presence and condition of the airbag computer supply voltage fuse.
Check that the computer connector is properly connected and check the condition of its wiring.
Check that the computer is correctly supplied:
– Disconnect the airbag computer and attach 22-track adapter (Elé. 1685).
– Check and ensure the presence of + after ignition feed between the terminals marked earth and
+ after ignition feed.
Ensure that the diagnostic socket is correctly supplied:
–+ Before ignition on track 16.
–+ after ignition feed on track 1
–Earth on tracks 4 and 5.
With 22-track adapter (Elé. 1685), check the continuity and insulation of the airbag computer / diagnostic
socket connection between:
Terminal block track CAN H Track 6 of the diagnostic socket
Terminal block track CAN L Track 14 of the diagnostic socket
If communication is still not established after these various tests, contact your Techline (see the "Help" section
for details).
AFTER REPAIRWhen communication is established, deal with any faults indicated.
ACU4 Vdiag04 J84 1.0
MR-372-J84-88C000$100.mif