BMW Cars 1999-06

General Information


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.

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.

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.

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.

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

Click image to see an enlarged view

Fig. The left side impact sensor shown mounted in front of the left front shock tower-E36 model shown

Click image to see an enlarged view

Fig. The right side impact sensor shown mounted in front of the right front shock tower near the washer reservoir-E36 model shown