Working on the electrical system of a car is dangerous since it can easily lead to accidental airbag employment. You shouldn't try it if you don't have relevant experience working on cars, especially the electrical systems in the dashboard. If you do decide to go ahead, take the following precautions to avoid injury and damage:

Disconnect the Battery

Disconnecting the negative battery terminal or removing power fuses cuts power to the airbag sensors. That way you don't have to worry about an accidental short circuit, which can set off the airbag. To disconnect the battery, switch off the engine, locate the negative cable (it is the black one, the red one is positive), squeeze the clamp to disconnect it, and secure it in place (for example with an electrical tape) so that it can't touch the battery. Disconnecting the battery also helps you to avoid electrical shocks.

Wait For the Backup to Discharge

Airbags don't rely fully on car batteries; they have backup batteries so that the airbags can work even if the car batteries are damaged. Therefore, after disconnecting the battery, give the backup battery a few minutes to discharge. If you don't, the airbag can still deploy accidentally due to its backup battery. Twenty minutes or so is enough to do the job.

Discharge Static Electricity

Even with the battery disconnected, there is still a small chance you may accidentally set off the airbag if you have static electricity. Static electricity is stored charge produced when two materials rub against each other. If your hands or tools have static electricity, the charges may cause airbag deployment when working on your car's electrical system. This risk is high if you are handling electrical wiring or circuits near the location of the airbags.

The solution is to discharge static electricity from your body. There are many different ways of discharging static electricity, but the easiest one is to touch a metallic material to drain the charges away.

Mind Your Electrical Modifications

Finally, you should be careful of any modifications you plan to make in your car's dashboard. Installing aftermarket gadgets, such as chargers and docking stations, in the area around or front of the airbag isn't advisable. Know your limitations so that you don't do anything that might lead to an electrical malfunction. If you aren't sure about something, take the cautious route and let it be handled by a professional mechanic. 

Working on the airbag directly isn't advisable. As it is such an important safety system, leave its servicing to a professional mechanic at a shop like Terwood Auto Repair.