MRS4 - System Overview
The MRS term, meaning Multiple Restraint system is adopted by quite a few Airbag system manufacturers, and this is no exception. This variation is the Bosch MRSZ4, and it Is quite sophisticated and complex for an Airbag system having a substantial number of configurable features and options to make it extremely flexible for many application requirements.
SM049 - MRS4 - System Help file
Version 1.27

MRS4 - Known Fitments
Vehicle makes, models and variants known or believed to be using this vehicle system, required diagnostic lead and degree of known compatibility.

Vehicle Make Vehicle Model Vehicle Variant Diagnostic Lead
Land Rover Range Rover MK III (L322) 2002 - 2009 Black OBDII Lead/LD020/LD021

MRS4 - Physical Details

SM049 - MRS4 - Diagnostic Capabilities (Read Fault Codes)
Reads the fault code memory. The ECU can self detect up to 61 different problems with itself, its wiring and its associated sensors, storing the respective code if it detects any malfunction or reading outside of pre defined acceptable limits. Not all stored faults may cause the fault warning lamp to illuminate.

SM049 - MRS4 - Diagnostic Capabilities (Clear Fault Codes)
Clears the fault code memory.

SM049 - MRS4 - Diagnostic Capabilities (Settings)
Values, configuration settings, and other stored information which can be read from the ECU, edited and then rewritten back. Read settings can also be stored as a standard HTML page for reference. These pages can then later be re loaded and re written back to the ECU. Please note that some values may be read only due to the fact that they are supplied from the ECUís ROM or are internally calculated.

  • Part Number: This is the manufacturer's part number for the ECU.
  • Hardware number: This is the hardware version which denotes the processor and circuit board type.
  • Software number: This denotes the coding inside the processor for the hardware.
  • Week of manufacture: This is the week of the year in which the unit was built.
  • Year of manufacture: This is the year in which the unit was built.
  • Supplier number: This is a number which defines the supplier using a standard look up list of supplier ECU manufacturer numbers.
  • Coding index: This is the coding identification for the programming maps.
  • Bus index: This is a number that indicates the bus communication support level, the vehicle communication buses.
  • Diagnostic index: This is a number that indicates the diagnostic capabilities support level.
  • Driver's Airbag Stage 1: This denote if the driver's airbag stage 1 is enabled or not.
  • Driver's Airbag Stage 2: This denote if the driver's airbag stage 2 is enabled or not.
  • Driver's Seat Belt Pretensioner: This denotes if the driver's seat belt pretensioner is enabled or disabled. When enabled, this will activate the pretensioners in case of a collision.
  • Driver's Seat Belt Fasten Switch: This denotes if the switch is enabled or not. When enabled, the switch will detect if the seat belt is fastened or not. If the seat belt is not fastened, the airbag will deploy at a high pressure.
  • Passenger's Airbag Stage 1: This denote if the passenger's airbag stage 1 is enabled or not.
  • Passenger's Airbag Stage 2: This denote if the passenger's airbag stage 2 is enabled or not.
  • Passenger's Seat Belt Pretensioner: This denotes if the passenger's seat belt pretensioner is enabled or disabled. When enabled, this will activate the pretensioners in case of a collision.
  • Passenger's Seat Belt Fasten Switch: This denotes if the switch is enabled or disabled. When enabled, the switch will detect if the seat belt is fastened or not. If the seat belt is not fastened, the airbag will deploy at a high pressure.
  • Front Left Side/Door Airbag: This denotes if the front left side airbag is enabled or disabled.
  • Front Right Side/Door Airbag: This denotes if the front right side airbag is enabled or disabled.
  • Font Left Head/ITS Airbag: This denotes if the front left head airbag (Inflatable Tubular Structure) is enabled or not.
  • Front Right Head/ITS Airbag: This denotes if the front right head airbag (Inflatable Tubular Structure) is enabled or not.
  • Rear Left Side/Door Airbag: This denotes if the rear left side airbag is enabled or disabled.
  • Rear Right Side/Door Airbag: This denotes if the rear right side airbag is enabled or disabled.
  • Rear Left Head/ITS Airbag: This denotes if the rear left head airbag (Inflatable Tubular Structure) is enabled or not.
  • Rear Right Head/ITS Airbag: This denotes if the rear right head airbag (Inflatable Tubular Structure) is enabled or not.
  • Rear Left Seat Belt Pretensioner: This denotes if the rear left seat belt pretensioner is enabled or disabled. When enabled, this will activate the pretensioners in case of a collision.
  • Rear Left Seat Belt Fasten Switch: This denotes if the switch is enabled or disabled. When enabled, the switch will detect if the seat belt is fastened or not. If the seat belt is not fasten, the rear passenger will hit the front seat during a collision. the front seat backrest will lock if the feature is fitted, to stop the movement (folding) of the front seat.
  • Rear Right Seat Belt Pretensioner: This denotes if the rear right seat belt pretensioner is enabled or disabled. When enabled, this will activate the pretensioners in case of a collision.
  • Rear Right Seat Belt Fasten Switch: This denotes if the switch is enabled or disabled. When enabled, the switch will detect if the seat belt is fastened or not. If the seat belt is not fastened, the rear passenger will hit the front seat during a collision. The front seat backrest will lock if the feature is fitted, to stop the movement (folding) of the front seat.
  • Rear Centre Seat Belt Pretensioner: This denotes if the rear centre seat belt pretensioner is enabled or disabled. When enabled, this will activate the pretensioners in case of a collision.
  • Rear Centre Seat Belt Fasten Switch: This denotes if the switch is enabled or disabled. When enabled, the switch will detect if the seat belt is fastened or not. If the seat belt is not fastened, the rear passenger will hit the front seat during a collision. The front seat backrest will lock if the feature is fitted, to stop the movement (folding) of the front seat.
  • Battery Cutoff Connector: The connector that disconnects the airbags system from the battery, located above the battery.
  • Battery Cutoff Switch: The switch that disconnects the airbags system from the battery.
  • Seat Belt Fasten Switch Two Wire Current: This denotes if the switch is enabled or not. When enabled, the switch using the two wire unipolar Hall effect, will detect the position of the driver in the car. The position will determine the way the driver's airbag will deploy.
  • Seat Belt Fasten Switch Four Wire Voltage: This denotes if the voltage switch is enabled or disabled.
  • Seat Occupation Detector-Standard (SBE 1): This denoted if the seat occupancy detector first generation is enabled or disabled. When enabled, this will determine if the seat is occupied, or vacant. This will determine the activation of the seat belt pretensioner and the deployment of the airbag (if the seat is vacant, the airbag will not deploy).
  • Seat Occupation Detector-Standard (SBE 2): This denoted if the seat occupancy detector second generation is enabled or disabled. When enabled, this will determine if the seat is occupied, or vacant. This will determine the activation of the seat belt pretensioner and the deployment of the airbag (if the seat is vacant, the airbag will not deploy).
  • Driver's Seat Backrest Lock: This denotes if the driver's seat backrest lock is enabled or not. The feature will lock the seat backrest in case of an impact.
  • Passenger's Seat Backrest Lock: This denotes if the passenger's seat backrest lock is enabled or not. The feature will lock the seat backrest in case of an impact.
  • Front MRSA: This enables the MRSA line when an extra front crash sensor is fitted.
  • Firing Configuration: This configure the way the airbag will fire. If the seat belt is not fasten, the airbag will deploy at high pressure.
  • Vehicle Hand: The hand side the vehicle is driven.
  • Auxiliary Lamp: This denotes if the auxiliary lamp is enabled or disabled.
  • Product Series Code: This is code of the product.
  • Coding Date (dd/mm/yyyy): This is the date the ECU was coded in DD/MM/YYYY format.
  • Coder Location ID Code: This is the code that denotes where the ECU was coded. 65 stands for the ECU coded in manufacturing (Solihull).
  • Coder ID: This is the ID of the coder.
  • VIN Number: The vehicle's identification number.
  • Lock Status: Denotes if the ECU is unlocked or locked. The ECU is locked only if new. This is not a reversing procedure, once locked, the ECU cannot be unlocked.
  • Crash Parameter 0 - 20: Coding data used in the configuration of the crash algorithm.
  • ID Data 1 - 2: Coding data used in the configuration of the ID.
  • MRSA Parameter 0 - 7: Coding data used in the configuration of the airbag ECU.
  • Spare Data: Data stored in the ECU used to configure the function of the ECU. Modification of the data produce unknown alteration in the functionality of the ECU.

SM049 - MRS4 - Diagnostic Capabilities (Inputs)
Realtime live display of the information the electronic control unit of the selected vehicle system is currently deriving from its input sensors.

  • Passenger seat: Detects if the passenger's seat is occupied or not. The status from occupied to unoccupied changes 3 minutes after the seat was vacated, or by recycling the ignition after the passenger left the seat.
  • Passenger fault: This indicates if the seat switch is faulty. When faulty, will not determine if the seat is occupied or not.