The headlights are protected by a circuit breaker in the headlamp switch. If the circuit breaker trips, the headlights will either flash on and off, or stay off altogether. The circuit breaker resets automatically after the overload is removed.
The windshield wipers are also protected by a circuit breaker. If the motor overheats, the circuit breaker will trip, remaining off until the motor cools or the overload is removed. One common cause of overheating is operation of the wipers in heavy snow.
The circuit breakers for the power door locks and power windows are located in the wiring harness in the engine compartment, on the firewall.
Circuit breakers differ from fuses in that they are reusable. Circuit breakers open when the flow of current exceeds specified value and will close after a few seconds when current flow returns to normal. Some of the circuits protected by circuit breakers include electric windows and power accessories. Circuit breakers are used in these applications due to the fact that they must operate at times under prolonged high current flow due to demand even though there is no malfuntion in the circuit.
There are 2 types of circuit breakers. The first type opens when high current flow is detected. A few seconds after the excessive current flow has been removed, the circuit breaker will close. If the high current flow is experienced again, the circuit will open again.
The second type is referred to as the Positive Temperature coefficient (PTC) circuit breaker. When excessive current flow passes through the PTC circuit breaker, the circuit is not opened but its resistance increases. As the device heats up with the increase in current flow, the resistance increases to the point where the circuit is effectively open. Unlike other circuit breakers, the PTC circuit breaker will not reset until the circuit is opened, removing voltage from the terminals. Once the voltage is removed, the circuit breaker will re-close within a few seconds.
Replace the circuit breaker by unplugging the old one and plugging in the new one. Confirm proper circuit operation.