Preliminaries

1. APPLICABILITY OF THIS DOCUMENT

This document describes the diagnosis applicable to all control units with the following characteristics:

Vehicle: MEGANE II Function concerned: AIRBAG

Control unit name: AUTOLIV - ACU 4 Program no.: Vdiag no.: 08

2. ESSENTIAL ITEM FOR DIAGNOSIS

Documentation type

Diagnostic methods (this document):

• Assisted diagnosis (built into the diagnostic tool), paper (Repair Manual or Technical Note), Dialogys.

Wiring diagrams:

• Visu-Schéma (CD-ROM), paper.

Diagnostic tool type

• CLIP

Essential tool type

ESSENTIAL SPECIALIST TOOLS

Multimeter Collection of adapters and terminal blocks for using the “Airbag and pretensioner harness check” function of the CLIP or XRBAG tools, at the update level including the terminal blocks listed below. The series change to the new airbag igniter connectors requires a change to the inert igniter. LOCAL MODIFICATION OF THE INERT IGNITER: Remove the igniter from its red holder and remove one of the two brown locking notches.

Control unit terminal block 22-way: Elé. 1685 64-way control unit terminal block: Elé. 1717 Seat terminal block 22-way: Elé. 1687 Rotary contact terminal block 10-way: Elé. 1617

3. REMINDERS

Procedure

To diagnose the vehicle's control units, put the ignition in diagnostic mode (+ after forced ignition):

• Place the vehicle badge on the badge holder.
• long press (more than 5 seconds) on the "start" button outside starting conditions,
• Then connect the diagnostic tool and carry out the required operations.

IMPORTANT

The left and right xenon headlamp control units are powered when the dipped beam headlights are switched on.

Their diagnosis is therefore only possible after switching the ignition on in diagnostic mode (or after forced ignition) and switching on the dipped headlights.

To switch off the +after ignition, proceed as follows:

• Disconnect the diagnostic tool,
• Briefly press the "start" button twice (less than 3 seconds each time),
• Check that the +after ignition forced is switched off by the computer warning lights on the instrument panel going out.

Faults

There are declared present faults and declared stored faults (which appeared under certain conditions and have since cleared, or are still present but were not diagnosed under the current conditions).

The “present” or “stored” state of faults must be considered when the diagnostic tool is started after + after ignition (without any action on the system components).

For a present fault, deal with the fault following the procedure given in the chapter "Fault interpretation".

For a stored fault, note the displayed faults and follow the instructions in the "Instructions" section.

If the fault is confirmed when the instruction is applied, the fault is present. In this case, repair the fault.

If the fault is not confirmed, carry out the basic checks. To do so, check:

• the electrical circuits corresponding to the fault,
• the connectors of these lines (corrosion, bent pins, etc.),
• the resistance of the component detected as faulty,
• the condition of the wiring (melted or cut insulation, chafing),

or use the diagnosis as a guide to check the circuit of the suspect component.

Conformity check: The purpose of the conformity check is to verify the states and parameters that do not display a fault on the diagnostic tool but are inconsistent. This step therefore allows you to:

• diagnose faults with no fault display that may correspond to a customer complaint,
• verify correct operation of the system and make sure a fault will not reappear after repair.

This chapter therefore contains a diagnosis of states and parameters, under the conditions required for their check.

If a state does not operate normally or a parameter is out of tolerance, refer to the corresponding diagnostic page.

Customer complaints - Fault locating tree

If the diagnostic tool check is correct but the customer complaint is still present, deal with the problem using "customer complaints".

A summary of the overall procedure is shown as a flowchart on the next page.

4. DIAGNOSTIC PROCEDURE

4. DIAGNOSTIC PROCEDURE

Wiring checks:

Diagnostic difficulties:

Disconnecting connectors and/or handling the wiring may temporarily eliminate the cause of a fault.

Electrical measurements of voltage, resistance and insulation are generally correct, especially when the fault is not present at the time of analysis (stored fault).

Visual inspection:

Look for damage under the engine hood and in the passenger compartment.

Carefully check the protection, insulation and routing of the wiring.

Look for signs of corrosion.

Touch test:

While manipulating the wiring, use the diagnostic tool to detect a change of fault state from "stored" to "present".

Make sure connectors are correctly locked, apply light stress to the connectors, twist the harness. If a change of state occurs, try to locate the source of the fault.

Inspection of each component:

Disconnect the connectors and check the condition of the clips and tabs as well as their crimping (no crimping on the insulating part).

Check that the clips and tabs are properly locked in the cavities.

Make sure no clips or tabs are pushed out when connecting.

Check the contact pressure of the clips using a tab of the appropriate type.

Resistance check:

Check continuity of the complete circuits, then section by section.

Look for a short to ground, to +12 V or to another wire.

If a fault is detected, carry out the repair or replacement.

5. DIAGNOSTIC SHEET

WARNING:

All incidents on a complex system must be subject to a full diagnosis using suitable tools. The DIAGNOSTIC SHEET, to be completed during diagnosis, provides and keeps a record of the diagnosis carried out. It is an essential element of communication with the manufacturer.

A DIAGNOSTIC SHEET MUST BE COMPLETED EVERY TIME A DIAGNOSIS IS PERFORMED.

This sheet will always be required:

• When requesting technical assistance from the techline.
• For approval requests, when replacing parts that require mandatory approval.
• Attach it to the "under surveillance" parts requested for return. It is then required for warranty reimbursement and helps with a better analysis of the removed parts.

6. SAFETY INSTRUCTIONS

Any work on a component requires compliance with safety rules to avoid any material or personal injury:

• Check that the battery is correctly charged to avoid damage to the ECUs in case of low charge.

When working on airbag and seat belt pretensioner systems, always lock the control unit using the diagnostic tool to prevent any risk of accidental deployment (all firing lines will be inhibited). This “locked” mode is indicated by the warning light on the instrument panel coming on.

If the diagnostic tool cannot connect, switch off the ignition, remove the system's power fuse and wait at least 2 seconds for the reserve energy capacitor to discharge.

Never take measurements on the airbag and pretensioner firing lines with any device other than the XRBAG or the “Airbag and pretensioner harness check” function of the CLIP.

Before using an inert igniter, make sure its resistance is between 1.8 and 2.5 Ω.

During the procedure, make sure the control unit supply voltage does not drop below 10 V.

WARNING

The destruction and disposal of airbags and pretensioners is subject to the legislation of each country.

SYSTEM CONFIGURATION SHEET (FRONT PART)

RR To rear wiring harness

SYSTEM CONFIGURATION SHEET (REAR PART)

Correct insulation value: display ≥ 100.h or flashing 9999.

DEFINITION OF FIRING LINES

L1: Driver's seat cushion / ventral airbag circuit (wire B of 64-way connector block Elé. 1717)
L2: Passenger's seat cushion / ventral airbag circuit (wire D of 64-way connector block Elé. 1717)
L3: Passenger front airbag circuit 1 (wire B of 22-way connector block Elé. 1685)
L4: Passenger front airbag circuit 2 (wire A of 22-way connector block Elé. 1685)
L5: Driver front airbag circuit 1 (wire C of 22-way connector block Elé. 1685)
L6: Driver front airbag circuit 2 (wire D of 22-way connector block Elé. 1685)
L7: Driver-side head side airbag circuit (wire I of 64-way connector block Elé. 1717)
L8: Passenger-side head side airbag circuit (wire G of 64-way connector block Elé. 1717)
L9: Driver-side front chest side airbag circuit (wire H of 64-way connector block Elé. 1717)
L10: Passenger-side front chest side airbag circuit (wire F of 64-way connector block Elé. 1717)
L11: Driver-side rear chest side airbag circuit (wire N of 64-way connector block Elé. 1717)
L12: Passenger-side rear chest side airbag circuit (wire L of 64-way connector block Elé. 1717)
L13: Front belt pretensioner circuits (wires A and C of 64-way connector block Elé. 1717)
L14: Rear retractors (wires E and J of 64-way connector block Elé. 1717)
L15: Driver-side rear front airbag circuit (wire O of 64-way connector block Elé. 1717)
L16: Passenger-side rear front airbag circuit (wire M of 64-way connector block Elé. 1717)