V70 XC AWD L5-2.4L Turbo VIN 56 B5254T (1998)
Clutch Switch: Description and Operation
Vacuum Valves (pedal valves)
The older type of valve is adjusted by turning the threaded piston sleeve in or out to achieve the desired disengagement position.
A spring-loaded piston activates a microswitch and a vacuum valve. The valve is self-adjusting, using small plastic tabs hook into the piston and
adjust it to the proper position.
Identical vacuum valves are located on the pedal assemblies. During adjustment, the pedal is depressed to allow the piston to be pulled out. The
pedal is then carefully released so that the piston is not pushed back too far. In the normal position, with the pedal up, the spring is compressed, the
switch is on and the vacuum valve is closed.
When the pedal is depressed, when braking or releasing the clutch, the spring pushes the piston back, breaking the switch contact and thereby
breaking the control module ground and opening its relay. Simultaneously, the vacuum valve is opened to allow atmospheric pressure into the
system, disengaging the cruise control.