Description
Autoliv Airbag Control Unit for Citroën Xsara Picasso
Overview
This Airbag Control Unit (SRS ECU) manufactured by Autoliv is designed for the Citroën Xsara Picasso. Commonly searched by part numbers 602327400, 9659111980 and 6556RA, this unit monitors crash sensors and controls deployment of airbags and seatbelt pretensioners to ensure occupant safety. The description and codes make it easy for mechanics and DIY enthusiasts to find the correct replacement quickly.
Why This Unit Matters
The airbag control unit is the central element of the vehicle restraint system. It continuously evaluates input from crash and seat sensors and decides whether to trigger airbag inflation during an impact. Besides triggering, it stores crash event data and system fault memories which are required for proper diagnostics after an incident. Replacing a faulty or deployed unit is critical for restoring full occupant protection.
How To Replace (General Guide)
Replacement should be performed by an experienced technician or a competent DIYer familiar with SRS systems. Typical replacement steps:
- Disconnect the vehicle battery and wait at least 2 minutes to allow residual system energy to dissipate (follow manufacturer recommendations).
- Locate the airbag control unit (commonly mounted in the passenger compartment; locations vary by specification — under the center console or secured to the body structure behind trim panels).
- Remove necessary trim and fasteners to access the unit, then disconnect electrical connectors carefully — avoid bending pins and clean any corrosion.
- Fit the replacement unit, secure fasteners to the correct torque, reconnect connectors and reassemble trim.
- Use a diagnostic tool to clear SRS fault codes, verify system communication and perform any required initialization. If the unit has crash data or deployment history, it will not restore protection until the issue is resolved and proper replacement procedures are followed.
Installation Recommendations
- Always disconnect the battery before starting work and follow the vehicle manufacturer’s service procedures to avoid accidental deployment or damage to the unit.
- Inspect connector pins and wiring harness for corrosion or damage; repair any poor contacts before installing the new unit.
- After fitting, verify system status with a suitable diagnostic scanner capable of reading SRS data and clearing fault memories. Confirm no persistent faults remain and perform a road test as per workshop procedures.
- Keep track of part numbers when ordering; many mechanics search by the original codes (602327400 / 9659111980 / 6556RA) to ensure correct fitment.
Common Causes Of Failure
- Deployment During A Collision — Once airbags deploy, the control unit typically requires replacement.
- Water Ingress Or Corrosion — Moisture reaching the unit or connectors can cause malfunctions and intermittent faults.
- Electrical Surges Or Short Circuits — Battery issues or faulty wiring can damage internal electronics.
- Connector Damage Or Poor Contacts — Vibration, loose connections or pin corrosion lead to communication errors and SRS warnings.
- Age And Environmental Stress — Long-term exposure to heat, humidity and vibration can degrade components over many years.
Technical Information
- Manufacturer: Autoliv
- Model: Citroën Xsara Picasso
- Product Codes: 602327400, 9659111980, 6556RA
- Additional Numbers: 602327400 | 9659111980 | 6556RA
Notes For Mechanics And DIYers
This unit is intended for use in the Citroën Xsara Picasso SRS system. Ensure you have the correct part numbers when replacing the module. After installation, a diagnostic check is mandatory to confirm correct operation. If the vehicle shows an SRS warning lamp after replacement, re-check connections and scan for stored fault codes to guide troubleshooting.
