The use of the Buick Relay on your vehicle is to assist in connecting an electrical device to the electrical system so it can be initiated upon the drivers demand. The relay on a vehicle is put into place for numerous reasons. It can reduce the voltage for an electrical component. It can also initiate the electrical current for numerous components at the same time.
The electrical system on your Buick is extensive but the electrical impulse it carries does not diminish in its system. For this reason the Buick relay for a component can be at one end of the vehicle and the device can be at the other. An example of this is the electrical fuel pump can have its relay under the dashboard of the Buick and still function as it was designed too. This is why when one of these electrical devices fail, pinpointing its location can be difficult. It can be literally anywhere on the vehicle.
When a relay is functioning properly, the owner of the vehicle can hear a slight clicking sound when the device is initiated. This is the contact of the electrical current being activated completing the circuit. When one of these electrical devices fails to initiate, no contact is made in the circuit and no sound can be heard.
The only information a wiring diagram can assist the owner of the Buick with in the location of a relay is the color code of the wires. To find assistance with its location, the use of a service manual can provide some information but a knowledgeable technician is the best source. Searching for the right one on your own can be very time consuming.