Air Bag Restraint Systems Land Rover Discovery L318

DESCRIPTION & OPERATION

The Supplemental Restraint System (SRS), also known as air bag system, is designed to provide additional protection for driver and front passenger by deploying air bags and front seat belt buckle pretensioners in a front-end collision. The air bags, stored in center of steering wheel and in instrument panel above glove box, deploy in about 40 milliseconds after impact sensors close. The seat belt buckle pretensioners are deployed in conjunction with the air bags. The air bag system is designed to be used with the 3-point seat belt system.

The main components of the air bag system are driver-side and passenger-side air bag modules, rotary coupler (clockspring), air bag Diagnostic Control Unit (DCU), left and right seat belt buckle pretensioners, and AIR BAG warning light (SRS warning light). See COMPONENT LOCATIONS .

COMPONENT LOCATIONS

Refer to illustration for component locations. (Scheme 1)

Scheme 1

SERVICING

Air bag modules must be replaced after 10 years from the date of manufacturer. Seat belt buckle pretensioners must be replaced after 15 years from the date of manufacture. Date of manufacture is located on certification plate attached to lock pillar (center pillar) of left front door.

SYSTEM OPERATION CHECK

Turn ignition switch to ON position. AIR BAG warning light should illuminate for approximately 5 seconds while air bag Diagnostic Control Unit (DCU) performs self-diagnosis. AIR BAG warning light will then go off if air bag system is functioning properly. If self-diagnosis by DCU reveals that a fault exists, AIR BAG warning light will go off for one second and then turn back on. Air bag system may not operate in the event of a collision if AIR BAG warning light is on. AIR BAG warning light will also come on if low voltage condition is present, but will go off when voltage condition is corrected.

AIR BAG SAFETY PRECAUTIONS

The following precautions should be observed when working with air bag systems

1. Disable air bag system before servicing any air bag system, interior trim, electrical system, steering column, or seat belt buckle pretensioner components. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system) .
2. Before attempting to service air bag system, remove key from ignition and disconnect both battery terminals. Air bag system has back-up power source which is capable of deploying air bags and seat belt buckle pretensioners for up to 10 minutes after battery cables are disconnected. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system) .
3. When placing a live air bag on a bench or other surface, ensure trim cover is facing up, away from surface. If air bag is stored face down, accidental deployment will propel module through air with force sufficient to cause serious injury.
4. DO NOT expose air bag system components to temperatures in excess of 185°F (85°C).
5. Air bag system faults can only be diagnosed using Land Rover Test Book tester. DO NOT use electrical test equipment while attempting to service air bag system. Disconnecting or probing air bag system connectors could result in accidental deployment or system damage.
6. If air bag module or other components have been dropped, or there are cracks, dents or other defects visible, replace with NEW parts.
7. DO NOT attempt to measure resistance across air bag module squib connector. Accidental air bag deployment is possible which could cause personal injury.
8. After deployment, air bag surface may contain deposits of sodium azide, a toxic, flammable substance. Always wear safety glasses, rubber gloves and long-sleeved shirt during clean-up. Wash hands using mild soap and water.
9. Never allow sodium azide to mix with water, acids or heavy metals. Harmful or explosive compounds can be produced.
10. Never attempt to incinerate or dismantle air bag or seat belt buckle pretensioner. After deployment, components will be very hot. Allow at least 30 minutes for cooling before handling air bag modules or pretensioners.
11. When carrying a live air bag module, make sure to face trim cover away from your body. In event of accidental deployment, this will reduce the risk of serious injury.
12. Never install used air bag system components from another vehicle. Always use NEW parts.
13. Always use NEW bolts (special Torx bolts for air bag modules) when installing any air bag system component. Ensure bolts are always tightened to correct torque.
14. Never install electrical or electronic equipment into air bag system electrical system. Air bag harness has a Yellow outer covering.
15. After work is complete on air bag system, ensure system is functioning properly. See «SYSTEM OPERATION CHECK»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__system-operation-check) .

DISABLING & ACTIVATING AIR BAG SYSTEM

DISABLING SYSTEM

Remove key from ignition switch. Disconnect negative, then positive battery cable. Wait 10 minutes before beginning work.

ACTIVATING SYSTEM

Ensure ignition switch is off and key is removed. Reconnect positive battery cable. Reconnect negative battery cable. Perform system operation check. See SYSTEM OPERATION CHECK .

DISPOSAL PROCEDURES

Disposal of undeployed components may be a violation of federal, state, and local laws. If a vehicle is to be removed from service (scrapped), air bag system components should be deployed while installed in vehicle. If this is impossible or if vehicle is being placed back into service, remove components and deploy outside vehicle. See OFF-VEHICLE DEPLOYMENT .

DEPLOYMENT TOOL TEST

1. Using Deployment Tool (SMD 4082/1), connect Blue and Yellow connectors of tool lead into corresponding sockets on face of deployment tool.
2. Connect alligator clips of tool lead to 12-volt battery (Red clip to positive terminal and Black clip to negative terminal). Red "READY" light on face of deployment tool should illuminate. Depress and hold both buttons on face of deployment tool. Green "DEFECTIVE" light should illuminate. Release both buttons. Red "READY" light will illuminate again. Disconnect tool from battery and disconnect Blue and Yellow connectors from face of tool. Tool is ready for use.

ON-VEHICLE DEPLOYMENT (SCRAPPED VEHICLES ONLY)

Seat Belt Buckle Pretensioner

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions) . Disable air bag system. See «DISABLING SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-system) under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform «DEPLOYMENT TOOL TEST»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__deployment-tool-test) .
2. Move front seat fully rearward. Disconnect Yellow seat belt buckle pretensioner harness connector, located under inboard side of front seat. Ensure Deployment Tool (SMD 4082/1) is not connected to battery. Connect Deployment Tool Lead (SMD 4082/30) to seat belt buckle pretensioner connector. Connect deployment tool lead to deployment tool. Ensure seat belt buckle pretensioner is secured to seat.
3. Move at least 50 feet (15.2 m) from seat belt buckle pretensioner. Connect deployment tool to battery. Ensure no one is within 50 feet (15.2 m) of seat belt buckle pretensioner. Depress both buttons on face of deployment tool to deploy seat belt buckle pretensioner.
4. Wearing safety glasses, rubber gloves and long-sleeved shirt, disconnect deployment tool from seat belt buckle pretensioner. Remove deployed seat belt buckle pretensioner from seat, place in sturdy plastic bag and seal.

OFF-VEHICLE DEPLOYMENT

Driver-side AIR Bag

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions). Disable air bag system. See «DISABLING SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-system) under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform «DEPLOYMENT TOOL TEST»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__deployment-tool-test). Position Air Bag Holding Fixture (SMD 4082/2) in vice. Ensure vice jaws grip tool above bottom flange. (Scheme 2)
2. Remove driver-side air bag module. See «DRIVER-SIDE AIR BAG MODULE»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems) under REMOVAL & INSTALLATION. Install driver-side air bag module onto air bag holding fixture, making sure that module is securely mounted.
3. Ensure Deployment Tool (SMD 4082/1) is not connected to battery. Connect Deployment Tool Lead (SMD 4082/4) to driver-side air bag connector. Connect deployment tool lead to deployment tool.
4. Move at least 50 feet (15.2 m) from air bag module. Connect deployment tool to battery. Ensure no one is within 50 feet (15.2 m) of air bag module. Depress both buttons on face of deployment tool to deploy air bag module.
5. Wait at least 30 minutes before proceeding. Wearing safety glasses, rubber gloves and long-sleeved shirt, disconnect deployment tool from air bag module. Remove deployed air bag module from holding fixture and seal in sturdy plastic bag.
6. If vehicle is to be scrapped, remove and dispose of all other air bag system components (including steering wheel and steering column) to ensure they are not reused.

Scheme 2

Passenger-side AIR Bag

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions). Disable air bag system. See «DISABLING SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-system) under DISABLING & ACTIVATING AIR BAG SYSTEM. Perform «DEPLOYMENT TOOL TEST»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__deployment-tool-test). Position Air Bag Holding Fixture (SMD 4082/6) in vice. Secure Brackets (SDM 4082/7) to holding fixture. Ensure vice jaws grip tool above bottom flange. (Scheme 3)
2. Remove passenger-side air bag module from vehicle. See «PASSENGER-SIDE AIR BAG MODULE»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems) under REMOVAL & INSTALLATION. Mount passenger-side air bag module on holding fixture and bracket. Ensure module is securely mounted.
3. Ensure Deployment Tool (SMD 4082/1) is not connected to battery. Connect Deployment Tool Lead (SMD 4082/5) to passenger-side air bag module connector. Connect deployment tool lead to deployment tool.
4. Move at least 50 feet (15.2 m) from air bag module. Connect deployment tool to battery. Ensure no one else is within 50 feet (15.2 m) of air bag module. Depress both buttons on face of deployment tool to deploy air bag module.
5. Wait at least 30 minutes before proceeding. Wearing safety glasses, rubber gloves and long-sleeved shirt, disconnect deployment tool from air bag module. Remove deployed air bag module from holding fixture and seal in sturdy plastic bag.

Scheme 3

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

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions). Disable air bag system. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system). Remove center console. See «CENTER CONSOLE»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems). Disconnect DCU connector. (Scheme 4) Remove 3 Torx bolts and remove DCU from vehicle.
2. To install, reverse removal procedure. Tighten DCU Torx bolts to specification. See «TORQUE SPECIFICATIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__torque-specifications). Activate air bag system.

Scheme 4

Removal & Installation (Automatic Transmission)

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions) . Place gearshift lever in "D" position. Remove gearshift lever knob and spacer. Release gearshift selector panel from console, disconnect electrical connector and remove panel. Remove transfer case lever knob. Release clips and remove transfer case lever boot.
2. On base trim models, remove rubber mat from center console then, remove cover plate from switch pack. Remove 4 screws, disconnect electrical connectors and remove switch pack. On veneer trim models, release veneer console cover and remove lighter element. Disconnect electrical connectors from switch pack and remove veneer trim with switch pack.
3. On all models, remove 2 bolts securing front of console to transmission tunnel. Release parking brake handle boot from console. Remove clip and clevis pin securing parking brake cable to lever. Move parking brake handle to fully up position.
4. Release power seat switches, disconnect connectors and remove switches from console. Remove 2 bolts securing rear of console to transmission tunnel. Release console from instrument panel, disconnect lighter and remove center console.
5. To install, reverse removal procedure. Use care when handling veneer.

Removal & Installation (Manual Transmission)

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions) . Release clips securing gearshift lever boot to console, remove gearshift lever knob and boot. Release clips securing transfer case lever boot to console, remove transfer case lever knob and boot.
2. On base trim models, remove rubber mat from center console then, remove cover plate from switch pack. Remove 4 screws, disconnect electrical connectors and remove switch pack. On veneer trim models, release veneer console cover and remove lighter element. Disconnect electrical connectors from switch pack and remove veneer trim with switch pack.
3. On all models, remove 2 bolts securing front of console to transmission tunnel. Release parking brake handle boot from console. Remove clip and clevis pin securing parking brake cable to lever. Move parking brake handle to fully up position.
4. Release power seat switches, disconnect connectors and remove switches from console. Remove 2 bolts securing rear of console to transmission tunnel. Release console from instrument panel, disconnect lighter and remove center console.
5. To install, reverse removal procedure. Use care when handling veneer.

Removal

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions). Turn steering wheel 90 degrees from horizontal. Disable air bag system. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system).
2. From behind steering wheel, remove 2 Torx bolts retaining driver-side air bag module to steering wheel. (Scheme 5) Lift driver-side air bag module away from steering wheel and disconnect connector. Remove air bag module from vehicle.

Note. If air bag module is being replaced, record bar code of air bag modules on air bag information sticker.

Installation

Connect driver-side air bag module connector. Position module on steering wheel and install Torx bolts. Tighten bolts to specification. See TORQUE SPECIFICATIONS . Activate air bag system.

Scheme 5

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions). Disable air bag system. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system). Remove bolts from glove box door hinge and remove glove box. Remove 4 Torx bolts retaining passenger-side air bag module to instrument panel. (Scheme 6)
2. Lift module out of instrument panel and disconnect connector from harness. Remove module from vehicle. If module is to be replaced, record serial number.

Note. If air bag module is being replaced, record bar code of air bag modules on air bag information sticker.

Connect passenger-side air bag module to chassis harness. Position module into instrument panel, and install Torx screws. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS . Install glove box. Activate air bag system.

Scheme 6

Before proceeding, see AIR BAG SAFETY PRECAUTIONS. Remove steering wheel. See STEERING WHEEL. Remove steering column covers. Disconnect rotary coupler connector from bracket and disconnect from harness. (Scheme 7) Remove rotary coupler from steering column. To install, reverse removal procedure. Activate air bag system.

Scheme 7

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions) . Disable air bag system. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system) . Remove 3 screws and one trim clip securing lower trim casing to seat and remove trim. Remove lower seat belt anchor bolt from rear outer corner of lower seat frame. Remove 4 Torx bolts securing seat to floor.
2. Tilt seat forward to disconnect electrical connectors. Remove seat from vehicle. Remove cable tie securing seat belt buckle pretensioner harness to seat frame. Remove Torx bolt attaching pretensioner to seat frame and remove pretensioner.
3. To install, reverse removal procedure. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__torque-specifications) . Activate air bag system.

1. Before proceeding, see «AIR BAG SAFETY PRECAUTIONS»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__air-bag-safety-precautions) . Disable air bag system. See «DISABLING & ACTIVATING AIR BAG SYSTEM»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems__disabling-activating-air-bag-system) . Remove driver-side air bag module. See «DRIVER-SIDE AIR BAG MODULE»(/land-rover/discovery/l318-2002-2004/remont/airbag/#air-bag-restraint-systems) .
2. Position front wheels in straight-ahead position. Loosen steering wheel nut. Release steering wheel from steering shaft (use puller if necessary). Remove and discard steering wheel nut. Remove steering wheel. Disconnect horn connector. Secure rotary coupler (clockspring) in position with tape to prevent movement.

Remove tape from rotary coupler (clockspring). Install steering wheel onto steering shaft. Connect horn connector. Install NEW self locking nut on steering shaft and tighten to specifications. See TORQUE SPECIFICATIONS . Install driver-side air bag module. Activate air bag system.

DIAGNOSTICS

Air bag system diagnostic information is not available from manufacturer. All air bag system diagnosis is accomplished using proprietary Land Rover Test Book or T4 diagnostic system.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Air Bag System Wiring Diagram (Discovery II). Scheme 8

See also:
• AIR BAG/SRS COMPONENT INSPECTION & REPLACEMENT TABLES
• AIR BAG SAFETY PRECAUTIONS
• COMPONENT LOCATIONS
• DISABLING & ACTIVATING AIR BAG SYSTEM
• SYSTEM OPERATION CHECK
• OFF-VEHICLE DEPLOYMENT
• DISABLING SYSTEM
• DEPLOYMENT TOOL TEST
• DRIVER-SIDE AIR BAG MODULE
• TORQUE SPECIFICATIONS