Solenoid S1 And S2

B8444S 

Fig 1: Identifying Solenoid S1 And S2

Courtesy of VOLVO CARS CORPORATION

Other engines 

Fig 2: Identifying Solenoid S1 And S2

Courtesy of VOLVO CARS CORPORATION

The solenoids S1 and S2 are located in the transmission control system, which is fitted on the front edge of the gearbox. The solenoids are the on/off type, and consist of an electrical coil which controls a hydraulic valve. The solenoids are supplied with 12 V power via the transmission control module (TCM) and are grounded in the control system. The solenoids control the gearshift and the transmission control module (TCM) activates the solenoids with engine braking for 1st gear.

The solenoids can be diagnosed.