Description & Operation: Notes

WARNING: This page is about a different car, the 1993 Mercedes-Benz 500SEL and 1993 Mercedes-Benz 500E. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: To avoid injury from accidental air bag deployment, read and carefully follow all WARNINGS and SERVICE PRECAUTIONS.

All models are equipped with Supplemental Restraint System (SRS). The main components of SRS are a driver-side air bag module, passenger-side air bag module, electronic SRS control unit, slip ring assembly with carbon contacts, energy accumulator (capacitor), a voltage transformer, SRS warning light, driver-side knee bolster and Emergency Tensioning Retractor (ETR) seat belt assembly. ETR seat belt assembly is standard equipment on passenger-side and optional equipment on driver-side. See Fig 1 .

If vehicle is equipped with passenger-side air bag, the air bag unit is installed in place of glove box, and incorporates a knee bolster. An Emergency Tensioning Retractor (ETR) is incorporated within passenger's seat belt assembly. The SRS is designed to be used with the 3-point seat belts.

If vehicle's deceleration rate, monitored by SRS control unit, is sufficiently high, SRS control unit delivers a voltage signal to ignite the gas generators in driver and passenger (if equipped) air bag modules, and in ETR seat belt tensioners. When gas generator solid propellant is ignited, a quantity of non-toxic nitrogen gas is produced. This nitrogen gas fills air bag in a few hundredths of a second. Immediately after air bag inflates to its maximum, gas is released through a ventilation hole on rear of air bag module, causing air bag to collapse. The entire sequence of air bag inflation and collapse takes about 0.2 second.

Fig 1: SRS Component Location (All Models)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.