Circuit Description
WARNING: This page is about a different car, the 2003 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.
This sensor sends 1 pulse per engine revolution to ECM.
If the number ratio of the compressor speed divided by the engine speed is smaller than a predetermined value, ECM turns the compressor OFF. And, the indicator flashes at about 1 second intervals.