System Overview: Components

Fig 1: Identifying Components In Control System For A/T

Courtesy of VOLVO CARS OF NORTH AMERICA.

The following components are included in the control system for automatic transmissions:

• Transmission control module (TCM) - Controls activation and deactivation of the solenoids by processing the signals from components such as the transmission input and output speed sensors and the temperature sensor. Also stores adaptive data as well as diagnostic trouble codes (DTCs) and frozen values for diagnostics
• Shift solenoid, S1 - Controls shifting in the transmission.
• Shift solenoid, S2 - Controls shifting in the transmission.
• Shift solenoid, S3 - Controls shifting in the transmission.
• Shift solenoid, S4 - Controls shifting in the transmission.
• Shift solenoid, S5 - Controls shifting in the transmission.
• Lock-up solenoid, SLU - Controls the lock-up function and is also used for certain shifts.
• Line pressure solenoid, SLT - Controls the line pressure in the transmission.
• Line pressure solenoid, SLS - Controls the transmission shifting pressure and is also used for certain shifts.
• Transmission input speed sensor (input shaft speed) (1) - Provides the transmission control module (TCM) with information about the input shaft speed from the engine
• Speed sensor (output shaft speed) (2) - Provides the transmission control module (TCM) with information about the output shaft speed from the transmission
• Oil temperature sensor (3) - Provides the transmission control module (TCM) with information about the oil temperature of the transmission
• Gear-shift position sensor, built-in to the transmission control module (TCM) (4) - Provides the transmission control module (TCM) with information about the selected gear
• Gear selector module (GSM) - Provides the transmission control module (TCM) with information about the Geartronic mode and winter mode (W).