Modulator Valve
- If necessary, remove modulator valve to access all vacuum fittings. Remove all hoses. Plug modulator No. 1 and No. 2 ports. Blow into hose located on bottom exhaust fitting of modulator to close diaphragm bleed. See Fig 1 .
- With a hand-held vacuum pump, apply 7 in. Hg to port No. 3 of modulator. Vacuum should hold. Release pressure from exhaust fitting hose to open diaphragm bleed. Vacuum on gauge should drop. If valve does not perform as stated, replace modulator valve.