Its best to treat the Airbag module as an explosive device, or a loaded gun, so treat it with respect. Even though it's rare there is a real possibility that an Airbag can set off with static electricity. Static can be build up easily on a dry day, so need to be extra carefull there. Do not wear silk material, shoes or slippers. Do not stand up on carpets. Whenever possible, touch metal parts of the vehicle handing removing/handling airbag. Ideally, should be strapped permanently to the vehicle earth/metal during this procedure.
In general, Airbags only has two electrical terminals, at least in E51. They are for the internal heating element which starts the chemical reaction for generating Nitrogen gas. Avoid touching them with fingers or get in contact with anything. As soon as the module is removed, keep it out of reach an out of harms way.
Disconnecting battery terminals
Removing battery terminals, and leaving the vehicle for few minutes for dissipating any residual power is very important. Technically it only requires removal of battery negative terminal, but for safe side it's a good practice to remove both terminals, pulled them back and make sure the connectors will not accidently spring back and come in contact with the battery. I tucked the wires away from the terminal and secured.
Keep the headlights ON, so it will drain any remaining electrical charge in the system.
Airbag module removal
The Airbag module is held by two screws, hidden away with plastic caps, either side of the steering wheel.
The plastic cap can be removed with even fingernails, but I used a fine flat-head screwdriver tip. It easily pops up.
Once the caps are off, there is a screw inside, which has a torx type security head. You need a matching security bit to remove these screws.
I didn't have them, so this was the ideal excuse to buy a set, which cost me $14 at Jaycar. Do not even attempt to use other tools on these screws, as they were designed to be used with specialized security bit. Otherwise
you may end up damaging the screw head easily, and render the screw unremovable. If that happens, drilling a screw close to an Airbag is asking for trouble. Use the right tools, and you will not be disappointed.
The screws are coated with threadlocker, so it will resist breaking the bond loose. Do not let the tooltip slip over the head, but a fitting security bit will do the job just fine. I used a ratchet arm, which gives more torque than a screwdriver. I would not recommend using a drill-driver anywhere close to the airbag. Hand tools works best. A consistent pressure, holding the bit perpendicular will get the first turn break free from the bond. Wobbly hands, and awkward angles may contribute to slippage, so be aware.
Removing wire connectors
Once the two screws are removed, the airbag module will release. It should be handled carefully and flip towards you, noticing the two wires holding it to the steering column. Center cable is for the Airbag, and left side is for the steering controls for stereo. These cables need to be disconnected. I choose to disconnect the airbag connector (yellow) first, due to obvious reasons.
The Yellow airbag connector is a specialized one, which can be removed only one way. That is to lift the black plastic, which disengages the connector lock. Slip a small flat-head screwdriver into the slot, and slightly lever down. The lock will pop open. Once the lock is opened, the yellow connector can be easily pulled out, from the socket.
This is very delicate, and you have to take the time and do it carefully, or otherwise a broken connector lock will render the airbag non functional. If it is broken for some terrible reason, do not try to fix it, get professional help replacing. That connector can be the decider of your life or death one day.
I may be over emphasizing and exaggerating the dangers of handling airbag. Probably I should do more, in my honest opinion. That is one device in the car, the driver depends life with. It's a no joke to render this invaluable safety device useless due to carelessness.
Once the airbag connector is out, next is the steering control connector. Usually called Clock Spring Connector. It's a gray plastic connector, with some pins unpopulated.This is pretty straight forward. Push the tab, and pull out the connector. I use a bent needle nose pliers to remove these type of connectors. It comes very handy in awkward locations where fingers cannot reach properly or not enough force can be exerted. Mine is a long arm one, which has a good reach.