Circuit Breaker (PTC)
WARNING: This page is about a different car, the 2008 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.
The PTC thermistor generates heat in response to current flow. The temperature (and resistance) of the thermistor element varies with current flow. Excessive current flow will cause the element's temperature to rise. When the temperature reaches a specified level, the electrical resistance will rise sharply to reduce the circuit current. This reduced current flow will cause the element to cool lowering the resistance accordingly. Once resistance falls to a specified level normal circuit current flow is allowed to resume.