2001-2007 Mercedes-Benz C Class Service & Repair Manual

2003 ACCESSORIES/SAFETY EQUIPMENT Mercedes-Benz - Air Bag Restraint Systems DESCRIPTION & OPERATION All models are equipped with Supplemental Restraint System (SRS). The main components of SRS are driver- side air bag module, passenger-side air bag module, side impact air bag modules (located in doors), SRS control module, side air bag sensors, SRS warning light, driver-side knee bolster, passenger-side knee bolster and seat belt pretensioners or Emergency Tensioning Retractor (ETR) seat belt assembly. Additionally, some vehicles may be equipped with head impact (curtain type) air bags. Both SRS and ETR are electronically activated by a single control module. There are 2 thresholds which must be exceeded to trigger an ETR action, air bag deployment, or both. If a moderately severe frontal collision occurs exceeding first triggering threshold where protection from seat belt is sufficient, only Emergency Tensioning Retractor (ETR) is activated if seat belt is buckled. If a moderately severe frontal collision occurs exceeding first triggering threshold where protection from seat belt is sufficient, but seat belt is not buckled, air bag is deployed and ETR is not activated. If a severe frontal collision occurs exceeding second triggering threshold where protection from seat belt is insufficient, air bag is deployed. ETR is activated if seat belt is buckled. If seat belt is not buckled, ETR is not activated when second triggering threshold is reached. Passenger air bag will deploy even if passenger seat is not occupied when a triggering threshold is exceeded. During certain types of collisions, the air bags will be deploy, but ETRs will not be activated. The side air bag on the driver-side deploys whenever the driver-side air bag module is deployed and when there is a substantial side impact crash. The air bag on the passenger-side will activate only when a sensor (Occupied Seat Recognition Sensor) in the passenger seat sends a signal to the SRS control module that the passenger-side seat is occupied. Side air bags mounted in rear doors will deploy when side impacts occur that exceed preset parameters. Head impact air bag modules will deploy when certain side impacts occur that exceed preset parameters. Head impact air bag will deploy independently of other air bags on side of impact. COMPONENT LOCATIONS COMPONENT LOCATIONS WARNING: Accidental air bag deployment is possible. Personal injury may result. Read and follow all WARNINGS and AIR BAG SAFETY PRECAUTIONS before working on air bag system or related components. Component Location AIR BAG warning light Instrument Panel Cluster Clockspring Under steering wheel Driver-side air bag module On steering wheel Emergency Tensioning Retractor (ETR) Driver-side & passenger-side lower B- & C-pillars (1) 2003 Mercedes-Benz C320 2003 ACCESSORIES/SAFETY EQUIPMENT Mercedes-Benz - Air Bag Restraint Systems 2003 Mercedes-Benz C320 2003 ACCESSORIES/SAFETY EQUIPMENT Mercedes-Benz - Air Bag Restraint Systems

SERVICING SRS AIR BAG label on driver-side door latch post indicates SRS replacement date for air bag units. All SRS components must be thoroughly inspected, including wiring harness. Before component replacement, check for SRS fault codes by performing system operation check. See SYSTEM OPERATION CHECK . SRS service life is 10 years from manufactured date or 10 years from SRS replacement date after accident related repairs are completed. SYSTEM OPERATION CHECK SRS warning light indicates SRS and Emergency Tensioning Retractor (ETR) system readiness. Turn ignition on. SRS warning light will illuminate, then turn off after approximately 4-6 seconds indicating SRS system is functioning properly. If SRS warning light does not illuminate, illuminates while driving or is continuously illuminated, there is a system fault. Repair malfunctioning system. AIR BAG SAFETY PRECAUTIONS Observe these precautions when servicing the air bag system:  When working around SRS components and before any repairs are performed, disable air bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM .  Before straightening any damage to body, or before performing electrical arc-welding, disable air bag system. See DISABLING & ACTIVATING AIR BAG SYSTEM .  Always wear safety glasses and gloves when handling a deployed air bag module. Air bag module may contain sodium hydroxide deposits which are irritating to the skin.  Always use control module and impact sensors made by same manufacturer. Using components produced by different manufacturers could cause accidental air bag or ETR deployment.  DO NOT repair any portion of SRS wiring harness.  If any SRS component is dropped from a height greater than 1.6 feet (0.5 m), it must be replaced.  If SRS components show signs of damage, they must be replaced.  Always handle air bag module with trim cover facing away from your body.  Always place air bag module on workbench with trim cover up, away from loose objects. Front Passenger Seat Occupied Recognition With Automatic Child Seat Recognition (ACSR) sensor Under passenger front seat cushion Head impact air bag modules Driver-side & passenger-side roof rails over front & rear doors Knee bolsters Driver-side and passenger-side lower instrument panel Passenger-side air bag module Passenger-side instrument panel Side impact air bag modules In front & rear doors Side impact sensors On floor inboard of door openings (1) On C Class, rear seat ETRs are part of seat belt buckle assemblies. 2003 Mercedes-Benz C320 2003 ACCESSORIES/SAFETY EQUIPMENT Mercedes-Benz - Air Bag Restraint Systems

 DO NOT expose any SRS component to temperatures in excess of 212°F (100°C).  DO NOT expose any SRS component to grease, oil or cleaning agents. DISABLING & ACTIVATING AIR BAG SYSTEM DISABLING SYSTEM Turn ignition off and remove key. Disconnect negative battery cable and shield cable end. Disconnect SRS control module electrical connector. ACTIVATING SYSTEM Connect SRS control module electrical connector. Ensure no one is in vehicle. Turn ignition on. Connect negative battery cable. Go to SYSTEM OPERATION CHECK . DISPOSAL PROCEDURES Several situations may arise requiring some form of disposal action, including:  Scrapping a vehicle containing deployed air bag modules and ETRs.  Scrapping a vehicle with live air bag modules and ETRs.  Disposal of a live but electrically faulty air bag module and/or ETR.  Disposal of a deployed air bag module and/or ETR. DEPLOYED AIR BAG OR ETR Deployed air bag modules and ETRs can be disposed of like any other part. SCRAPPED VEHICLE Undeployed air bag modules and ETRs CANNOT be disposed of without first being deployed. Contact manufacturer for additional information. UNDEPLOYED AIR BAG OR ETR Undeployed air bag modules and Emergency Tensioning Retractor (ETR) seat belts CANNOT be disposed of without first being deployed. Contact manufacturer for additional information. POST-COLLISION INSPECTION When a vehicle has been involved in a collision, certain components of the passive restraint system must be inspected or replaced. See AIR BAG/SRS COMPONENT INSPECTION & REPLACEMENT TABLES article in the GENERAL INFORMATION section. REMOVAL & INSTALLATION 2003 Mercedes-Benz C320 2003 ACCESSORIES/SAFETY EQUIPMENT Mercedes-Benz - Air Bag Restraint Systems

Removal and installation information is not available. DIAGNOSTICS Air bag system diagnostic information is not available. All air bag system diagnosis must be carried out using manufacturers proprietary test equipment. WIRE REPAIR If any part of SRS wiring harness is damaged, DO NOT repair wiring harness, replace complete wiring harness. WIRING DIAGRAMS Wiring diagrams are not available. WARNING: Accidental air bag deployment is possible. Personal injury may result. Read and follow all WARNINGS and AIR BAG SAFETY PRECAUTIONS before working on air bag system or related components. 2003 Mercedes-Benz C320 2003 ACCESSORIES/SAFETY EQUIPMENT Mercedes-Benz - Air Bag Restraint Systems

2001-2007 Mercedes-Benz C Class Service & Repair Manual

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