My 1993 Toyota 4 cylinder pickup has 4 vacuum switching valves. The 4th one is in front of the 3 and the tubes go to the idle up valves on the intake manifold. The wiring diagram shows 3 vacuum switching valves. The wires are blue and black with red stripe. When my tone tool sends tones on the blue wire, it shows up in nearly every wire. Does anyone know anything about this vacuum switching valve?

My truck has no spark. I’ve replaced the igniter aka ignition control module and air mass meter. I’ve tested the coil and pickup coil aka signal generator.