Steering wheel compatibility

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Steering wheel with airbag
Basically every BMW steering wheel that was manufactured during the BMW 8 Series years of production (1989–99) can be installed in the E31 without modifications or minor modifications at most. The steering wheel compatibility is not limited to steering wheels manufactured for the E31. For example; the 3-spoke M Technic steering wheel airbag from the 1995–99 E36 M3, which was never available for the E31, can be installed as well.

In April 1999 BMW introduced dual-stage airbags. Up until then all airbags used by BMW were single-stage airbags. A single-stage airbag has a single explosive charge to deploy the airbag – the speed and duration of deployment cannot be controlled: The airbag always deploys with the same force regardless of the speed of impact. A dual-stage airbag on the other had has two charges. A common misconception is that one charge is for low-speed impacts and the other for high-speed impacts. This is incorrect: Both charges are always required for proper deployment of the airbag, but they are not ignited at the same moment. By adjusting the delay between the ignitions the speed and duration of the airbag deployment can be controlled. This allows the airbag deployment to be adapted to the severity of the impact.

Although manufactured up to May 1999 – two months after the introduction of the dual-stage airbags – the BMW E31 8 Series was never updated to dual-stage airbags. This means no E31 is capable of using dual-stage airbags and limits the choice of steering wheels to those that have a single-stage airbag. Some people claim steering wheels with dual-stage airbags can be installed without problems by connecting only one of both stages. While this will not throw error messages in the airbag system and thus appears to be working correctly, the airbag will not deploy properly in a crash!

Note that some steering wheels from the E31 era were updated to dual-stage airbags. These steering wheels look the same on the outside but are incompatible with the E31! For these steering wheels it is however possible to install the single-stage airbag from the older version in the newer steering wheel, making it compatible with the E31. Some steering wheels were also available with multifunction buttons. These steering wheels can be installed in the E31 as well. Please note the E31 has no native support for multifunction steering wheels, but adapter modules are available to enable cruise control and radio control from the steering wheel buttons.

In more recent years the slip ring was moved from the steering wheel to the steering column. These steering wheels cannot be installed in the E31 without considerable modifications and machining of the steering wheel base. Worse is that no compatible single-stage airbags are available for these recent steering wheels. In other words; with some effort the steering wheels can be installed in the E31, but the airbag will never work properly.

Installing an airbag steering wheel in a car that is not equipped with airbag system is perfectly possible, but obviously the airbag will never deploy in the event of a crash. Other than that there are no issues. The other way around, installing a steering wheel without airbag in a car that was originally equipped with airbag, is possible as well but will trigger the airbag malfunction warning light in the instrument cluster. The warning light cannot be reset because the fault condition (the absence of the airbag) remains present. This reminds the driver permanently the airbag is not working. If this is undesirable behavior it can be avoided by jumping the airbag connector with a 3.3 Ω ¼ W resistor fooling the airbag system in thinking an airbag is connected.