Circuit Operation

The A/T control relay supplies battery positive voltage to the solenoid valve assembly (terminals 9 and 10).
The solenoid valve closes when energized (on), and opens when not energized (off). The PCM energizes the solenoid valve based on input data from sensors such as the Throttle Position Sensor, Park/Neutral Position Switch, Stoplight Switch, Input Shaft Speed Sensor, Output Shaft Speed Sensor, and A/T Fluid Temperature Sensor.
The PCM provides the ground to energize the solenoid. The amount of time that the circuit is grounded is displayed on scan tool MB991502 in percent.
When the solenoid is energized or de-energized, fluid passes through the valve body and transaxle passages to apply and release components.