240 L4-2320cc 2.3L SOHC VIN 83 B230FD (1993)
These are identical. A spring loaded piston actuates a microswitch and a vacuum valve.
In normal position, with the pedal up, the spring is compressed,the switch contacts are closed and the vacuum valve is closed. Terminal 3 of the
control unit is grounded via the brake lights and the control unit controls the negative pressure in the system.
When the pedal is depressed, for braking or declutching, the spring forces the piston back. This opens the switch contacts, so that the ground circuit of
the control unit terminal 3 opens and deenergises the relay. At the same time the vacuum valve opens, admitting ambient air and disengaging the cruise
control.
The vacuum valves are adjustable by means of threads on the piston sleeve, so that the vacuum valve can be unscrewed or screwed in to obtain the
desired disengagement position.
WARNING! This adjustment must NOT be used as a pedal stop. If the vacuum valves are adjusted incorrectly, the cruise control may not work properly
because the pedals have to be pressed too far before the cruise control is disengaged.
The brake light switch acts as an extra safety feature. If the brake pedal is pressed but the vacuum valve does not open, the current to the brake lights
will break the control unit ground circuit and stop the vacuum pump.
The clutch pedal vacuum valve works in the same way as that of the brake pedal, this prevents overrevving of the engine.
Special conditions
