VW Passat & Audi A4 1990-2000

General Information

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The Air Bag is referred to as a Supplemental Restraint System (SRS) component because it is designed to work with, or as a supplement to, the seat belts supplied with the vehicle.


CAUTION
Air bags should never be assumed to take the place of seat belts. The air bag is designed to work in conjunction with the seat belts. Most states have instituted laws requiring the use of seat belts. Consult your local and state laws regarding seat belt usage.


WARNING
If the air bags have deployed, the air bags, SRS control unit, and if installed, the seat belt tensioner assemblies must be replaced.

A basic SRS is comprised of the following components:



SRS Airbag
 
SRS Sensors
 
SRS Control Unit
 
Steering wheel contact ring
 
SRS Indicator Light (SRS Warning Light)
 

The SRS Sensors are used by the SRS Control Unit to detect a moderate to severe frontal collision. If such is the case, the SRS Sensors send a signal to the SRS Control Unit, which in turn activates the SRS Airbag. The SRS Control Unit also has it's own emergency backup power in case the vehicle's electrical system is disconnected in a crash.

The SRS Control Unit also monitors the integrity of the SRS System once the ignition key is switched ON . Under normal operating conditions, when the ignition key is initially turned to the ON position, the SRS Indicator Light should come on for 6 seconds, and then go out. This serves as a bulb check for the SRS Indicator Light. If the SRS Control Unit detects a problem in the SRS system, the SRS Indicator Light will remain ON until the problem is resolved and the SRS Diagnostic Trouble Codes (DTCs) erased.


CAUTION
If the SRS Indicator Light fails to light, or is on continuously, the cause should be determined immediately. The system may have a problem that could compromise the safe operation and/or deployment of the SRS system.

The SRS control unit has a fault memory, which can be accessed using a suitable Diagnostic Scan Tool (DST) such as the VAG 1551 or VAG 1552 connected to the 16-pin Data Link Connector (DLC).



Click image to see an enlarged view

Fig. The front air bags are designed to deploy in a severe frontal impact that occurs within 30° of the vehicle's centerline

SERVICE PRECAUTIONS

WARNING
The Supplemental Restraint System (SRS) must be disabled before performing service on or around system components, steering column, instrument panel components, wiring and sensors. Failure to follow safety and disabling procedures could result in accidental air bag deployment, possible personal injury and unnecessary system repairs.

Please take note of the following precautions whenever working on or near SRS air bag system components:



When carrying a live air bag module, point the bag and trim cushion away from your body. When placing a live air bag on a bench or other surface, always face the bag and trim cushion up, away from the surface. Following these precautions will reduce the chance of injury if the air bag is accidentally deployed.
 
Use only a digital multimeter when checking any part of the air bag system. The multimeter's output must be 0.01Amps (10mA) or less when it is switched to its smallest ohmmeter range value.
 
Do NOT bump, strike, or drop any SRS component. Store SRS components away from any source of electricity, including static electricity, moisture, oil, grease, and extreme heat and humidity.
 
Do NOT cut, damage, or attempt to alter the SRS wiring harness or its yellow insulation.
 
Do NOT install SRS components that have been recovered from wrecked or dismantled vehicles.
 
Always disconnect both battery cables when working around SRS components or wiring.
 
Always disable the air bag when working under the dashboard.
 
Always check the alignment of the air bag cable reel during steering-related service procedures.
 
Take extra care when working in the area of the dashboard. Avoid direct exposure of the SRS unit or wiring to heat guns, welding, or spraying equipment.
 
NEVER carry the inflator module by the wires or connector on the underside of the module.
 
When carrying a live inflator module, hold securely with both hands, and ensure that the bag and trim cover are pointed away.
 
Place the inflator module on a bench or other surface with the bag and trim cover facing up.
 
With the inflator module on the bench, never place anything on or close to the module which may be propelled in the event of an accidental deployment.
 



Click image to see an enlarged view

Fig. If removed, always place the inflator module facing up to avoid injury should accidental deployment occur



Click image to see an enlarged view

Fig. Cut away view of a spring-loaded SRS electrical connector. NEVER modify any SRS component



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Fig. During removal, keep your body hands and fingers away from the center portion of the air bag should it accidentally deploy



Disconnect the driver's/front passenger's air bag and if equipped, the seat belt tensioner connections before working below the dashboard close to the SRS control unit.
 
If the vehicle is involved in a frontal impact or after a collision without airbag deployment, inspect the SRS unit for physical damage. If the SRS control unit is dented, cracked, or deformed, replace it.
 
If removed or replaced, make sure the SRS control unit is installed securely.
 
NEVER disassemble the SRS control unit.
 
When installing or replacing the SRS control unit, be careful not to bump or strike the area around the SRS control unit. Avoid using impact wrenches, hammers, etc. in the area surrounding the SRS control unit
 
NEVER reach through the steering wheel to start an air bag equipped vehicle.
 
If the air bag has deployed, the air bags, control unit, and if equipped, the seat belt tensioners must be replaced.
 
Individual components of the air bag system must always be replaced rather than repaired
 
Do NOT treat air bag system components with grease or cleaning agents
 
Avoid physical contact with a deployed air bag. Wear protective equipment such as necessary
 
Do NOT expose air bag components to temperatures above 167°F (75°C)
 
Replace any air bag component that has been dropped a distance of 1 1 / 2 feet (0.5 m) or more
 
A replaced component of the air bag system must always be properly disposed of
 

DISARMING THE SYSTEM
  1. Place the ignition switch in the OFF position.
  2.  
  3. Disconnect the negative battery terminal and cover the battery terminal to prevent accidental contact.
  4.  

ARMING THE SYSTEM
  1. Place the ignition switch in the OFF position.
  2.  
  3. Attach the sensors, the steering column connector and the seat belt tensioner connectors.
  4.  
  5. Place the ignition switch in the ON position.
  6.  
  7. Connect the negative battery terminal.
  8.  


CAUTION
When turning the ignition switch ON and OFF, do not access the ignition switch by reaching through the steering wheel. Keep a safe distance between the steering wheel. Do NOT allow any loose objects near the air bag unit(s) when turning the ignition ON.

  1. Check the warning light operation by turning the ignition switch to the OFF position, then, turn the ignition switch to the ON position. Check that the SRS air bag light illuminates for 6 seconds and extinguishes. If it illuminates in any other pattern, check the components and their connections for proper operation and recheck the operation of the warning light.
  2.  

 
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