Switches are one of the key components of any electrical circuit. Switches are used in a multitude of locations for just about every conceivable vehicle accessory and feature. They range from the simple to the complex, some having just a few contacts while others have a complex arrangement for more sophisticated needs. An example of a simple switch is the one operated by the glove box door that turns on the light inside.
On the other end of the spectrum, the turn signal switch is rather complex, as it must control the turn signals, while interrupting the brake light circuit. Some switches are operated manually, such as the switches for the power windows. Other switches activate automatically, such as the door switches that activate the interior lights. Some switches, such as the headlight switch, may also include a circuit breaker as part of the switch assembly.
Switches open and close the various circuits on your car, providing control of those circuits. In circuit with higher current flow, a switch may be used indirectly for circuit control. That is, the switch activates a relay that actually handles current flow for the circuit.
The switches on your car do not require regular maintenance and usually last the life of the car. Nevertheless, switches can fail over time after being activated thousands of times during their normal life. The symptoms of a bad switch usually include a circuit that won't work at all or a circuit that may not work in certain modes. There are many things that can go wrong with an electrical circuit, a switch being just one of them. To accurately pinpoint the cause, have your car's electrical problem thoroughly diagnosed by a qualified service technician.