What are the electrical parts and where are they located? 

Your car contains a number of systems that run on electricity.  These include lights, fans, sensors, windows, locks, and many other parts run by small motors.  The battery powers all of these through ancillary circuits that are connected or disconnected by various fuses, relays, and switches.  Many ancillary circuits are wired through the ignition switch, so they can only be turned on when the switch is in the “accessory” or “on” positions.  Power is grounded to the vehicle’s frame at various points.  The frame is connected to the battery’s negative terminal by a cable. 

How do I know if my electrical parts need to be replaced?       

Electrical parts can burn out over time—especially from frequent use.  Sudden surges in power can also cause damage, but thankfully relays and fuses can protect the electrical parts by disconnecting them from their power source.  Often, a problem that seems like a damaged electrical part can be attributed to a blown fuse or a malfunctioning relay.  Before replacing an electrical part, you might want to check its corresponding fuse or relay.  You can find them in an electrical box under the hood.  Your owner’s manual will help you figure out which fuse or relay is which.  You can then replace the old one with a new one of the same type and see if that improves your situation.  If not, then you may have to replace the part in question.  You can test many electrical parts with a multimeter.  This often involves removing the part.  If the part does turn out to be broken, though, you’ll already be halfway through replacing it. 

Can I install the electrical parts myself?  

The difficulty of replacing electrical parts varies from vehicle to vehicle and part to part.  Relays, for example, can be very easy to replace.  You simply need to locate and open the electrical box, pull out the old relay, and push on the new one.  Parts like sensors, fans, actuators, and motors can be harder to access.  You may need to remove panels or other nearby parts to reach them.  Once you’ve found an electrical part, generally, you’ll just have to disconnect its electrical connector and unbolt it, then connect the new one and bolt it on.  Most of these parts can be replaced with a little bit of effort and patience.  Be sure to disconnect the battery before working with any electrical parts for safety’s sake.