The electronic control system of
Honda automatic transmissions consists of the transmission control module (TCM),
sensors, and four solenoid valves. Shifting and converter lockup are
electronically controlled. Activating a shift solenoid valve changes modulator
pressure, causing a shift valve to move. This allows pressurized fluid to flow
through a line to engage the appropriate clutch and its corresponding gearset.
Converter lockup is controlled by the action of the other two solenoid valves.
By receiving information from its input sensors, the TCM calculates the required
gear changes and energizes or de-energizes the shift solenoids.
The TCM receives information about
the throttle position, engine coolant temperature, engine speed, A/C on/off,
brake on/off, vehicle speed, and the speed of the transaxle's counter shaft.
Based on this information and the shift schedule and logic in the TCM, the
transaxle is shifted to meet the current operating requirements of the vehicle.