Yes, the vacuum line connects to full intake vacuum. Voltage from the ignition switch goes to a closed switch at the brake pedal, then to the vacuum switch, and from there to the transmission. Inside, it passes through a governor pressure switch that prevents converter lockup below a set speed, usually somewhere near 45 MPH. Any time the engine gets under a load, such as going up a steep hill, or passing, the vacuum drop disconnects the power, causing the converter to unlock. The vacuum switch and the governor switch are in series, so all must be closed to power up the Converter locking solenoid, and opening either one, or all of the switches stops the lockup. Applying brakes, dropping speed, or low vacuum disconnects the lockup clutch.
That way, it's impossible to get the car stopped with the converter locked in, which would stall the engine like stopping with a manual clutch engaged. Thr toggle switch some people use isn't that idiot-proof!
Jerry
