Line pressure solenoid, SLT

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Volvo S80, 2005 Volvo S80, 2004 Volvo S80, 2003 Volvo S80, and 2002 Volvo S80. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Line Pressure Solenoid (SLT)

Courtesy of VOLVO CARS OF NORTH AMERICA.

The line pressure solenoid, SLT is in the gearbox control system, which is mounted on the front edge of the gearbox. The line pressure solenoid, SLT consists of an electric coil which controls a hydraulic valve. The solenoid is controlled by pulse width modulation (PWM) voltage and is grounded via the control module. The solenoid is linear. The hydraulic valve is controlled by the varied current which is the result of the current pulse conditions. During high pulse conditions, (at high currents (approximately 1 A)) the line pressure is low. During low pulse conditions (at low currents) the line pressure is high. The solenoid also engages and disengages neutral control. In the event of an open-circuit the line pressure reaches maximum which causes hard shifting. The hydraulic valve is then completely open.

There are diagnostics for the solenoid.