Anti-lock braking systems (ABS) on many 4-wheel drive vehicles contain mercury switches. The switches are in a G-Force sensor that detects deceleration and takes the vehicle out of 4-wheel drive during slipping. Some ABS sensors have two mercury switches and others have three.
Not all vehicles with ABS sensors have mercury switches. General Motors, for example, never used mercury switches in ABS. As of model year 2004, mercury switches were phased out of ABS in all vehicles.
A list of vehicles that use mercury switches in the ABS can be found in the "Vehicle Mercury Light Switch Removal Guide" (Washington State Department of Ecology).
ABS G-Force sensors consist of two or three mercury switches embedded in plastic. The plastic sensor is about the size of a credit card and weighs 3 – 4 ounces. The "Vehicle Mercury Light Switch Removal Guide" (Washington State Department of Ecology) describes where these sensors are typically found and how to remove them.
Store mercury sensors in a leak-proof, closed plastic container—it can be the same one used for storing mercury light switch assemblies.
For more information contact Taylor Watson, Health and Environmental Investigator, at firstname.lastname@example.org.