Additional Wiring
WARNING: This page is about a different car, the 2007 Chrysler PT Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
For complete wiring diagrams, refer to SYSTEM WIRING DIAGRAMS article.
Pressure switches are normally off or open (no pressure applied) and read high (+12 volts). When an element is applied, the corresponding pressure switch closes to ground. The controller tests the OD and 2/4 pressure switches when they are off (when the corresponding friction element is not applied) by briefly applying the OD and 2/4 elements which will cause the corresponding pressure switch to close. The test verifies that the switches are operational and that the switch will close when the corresponding element is applied. If a switch fails to respond, it is re-tested and if the test fails two times the transmission defaults to limp-in mode and the MIL illuminates.