Theory Of Operation

WARNING: This page is about a different variant/trim than selected.

The transmission output from the PDC is used to supply power to the solenoid pack when in normal operating mode and to turn off power to produce transmission "limp-in" mode. The PDC transmission output (which supplies power to the solenoid pack) is fed back to the controller. It is referred to as SWITCHED BATTERY. After a controller reset (ignition key turned to the RUN position or after cranking engine), the controller verifies that the PCM/TCM Relay is not energizing the output by checking for no voltage on Switched battery line (TCM power input) before the command is sent to the relay to energize the output. After switched battery is verified for no voltage, the voltage of each of the solenoid pack pressure switches is also checked. Since the solenoid pack is not powered up, there should be no voltage on any of the pressure switches.