SIEMENS AIRBAG 1 - System Overview
Introduced in 2002 in the Freelander, this ECU replaced the Sagem AC4.
SM071 - SIEMENS AIRBAG 1 - System Help file
Version 1.22

SIEMENS AIRBAG 1 - 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 Freelander 2002> Black OBDII Lead

SIEMENS AIRBAG 1 - Physical Details

SM071 - SIEMENS AIRBAG 1 - Diagnostic Capabilities (Read Fault Codes)
Reads the fault code memory. The ECU can self detect up to 22 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.

Each airbag system can self detect up to 24 faults. Most of these are major or safety related faults causing full system shutdown with only a few being minor caused by, for instance a flat battery. The systems perform a self-diagnostic test that takes about 15 seconds whenever the ignition is switched on, logging any faults that are found, and then at regular intervals thereafter. There is a deep memory within the airbag ECU that keeps a long-term record of resets to detected faults. This means that if a particular connection was poor and went open circuit - even just once - the fault would be logged by the system as - a sensor is open circuit - and the airbag warning light would come on. If the fault was not found and the fault code memory was cleared it would be very likely to reappear. This would be logged as an intermittent fault within the system.

SM071 - SIEMENS AIRBAG 1 - Diagnostic Capabilities (Clear Fault Codes)
This function checks the fault code memory for resident faults and clears the fault code memory if the fault has been rectified. Having deleted the faults the system then rechecks the fault memory to ensure that it is clear. Failure to clear the fault memory successfully is usually due to the system re-logging the fault the moment the fault memory is clear, meaning that the fault has not been rectified properly and as far as the system is concerned, still exists. The system may also carry out a re-check for successful clearing of the fault code memory but then the system may re-log the fault shortly after.

SM071 - SIEMENS AIRBAG 1 - 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.

  • Last 5 digits of VIN number: This are the last 5 digits of the vehicles VIN number. It can only be written once. When it has not been written, eg a new ECU, you will see N/A appear.
  • Numbers of doors: This is the vehicle's number of doors. This information can be written only once. When it has not been written it will display N/A.
  • 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.
  • Serial number: The electronically stored serial number for this airbag ECU, and can be found printed on a label affixed to the top or side of the ECU.
  • Coding index: This is the coding identification for the programming maps.
  • Software version: Gives the software version number for this airbag ECU.
  • Hardware version: Gives the hardware version number for this airbag ECU.
  • Part number: This is the manufacturer's part number for the ECU.
  • Configuration: This value denotes the configuration of the airbag system and it is translated in fitment or omission of the airbag, fitment or omission of the pretensioner, fitment or omission of the pretensioner, cash lock and inhibited firing.
  • Coding 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.
  • Right hand pretensioner/ Left hand pretensioner: This denotes fitment or omission of the right hand/left hand seat belt pretensioner.
  • Driver's front airbag/ Passenger's front airbag: This denotes fitment or omission of the driver's/passenger's airbag.
  • Driver's seat belt switch / Passenger's seat belt switch: This denotes fitment or omission of the driver's/passenger's seat belt switch.
  • Inhibited firing: This denotes if the firing of the airbag is inhibited or not.
  • Crash lock: This denotes if the airbag ECU is locked or not due to a crash.
  • Driver seat belt switch: This denotes fitment or omission of the driver's seat belt switch.
  • Passenger seat belt switch: This denotes fitment or omission of the passenger's seat belt switch.