History of Multiple Restraint Systems: MRS4RD: Notes

The multiple restraint system 4 redesign MRS4RD is a development of the MRS4 on the E46. The MRS4RD has had its interfaces expanded to 75 pins.

The job of the MRS4RD is to detect accident scenarios that are critical for the vehicle occupants and to selectively activate the necessary restraint systems according to the severity of the crash.

The MRS4RD has been further optimized and equipped with the following sensors:

• Up-front sensors
• Door-compression sensors
• B-pillar satellites

The job of the up-front sensors is to detect frontal impacts. This allows the restraint systems such as seatbelt tensioners and airbags to be activated.

The job of the door-compression sensors is to detect side impacts The MRS4 satellites (MRSA) under the front seats have been moved to the B-pillars. The B-pillar satellites contain acceleration sensors for linear and lateral acceleration.

The MRS4RD performs a self-diagnosis and monitors all input and output signals. Any faults detected are stored in a non-volatile memory and indicated to the driver by the airbag warning lamp (AWL).

Communication with other control units in the vehicle's network of systems takes place via the K-bus.

The MRS4RD can be programmed/encoded via the K-bus.