The neutral safety switch on a 2005 GMC Sierra is located on the
transmission. It's not easily accessible without some mechanical knowledge and will likely require working underneath the vehicle. It's usually attached to the side of the transmission near where the shift linkage connects.
Important Note: Because of its location and the need to work under the vehicle, locating and replacing this switch is usually considered a job for a mechanic unless you have experience working on vehicles. Improper installation could lead to safety issues.
