Automatic Transmission

Start engine with transmission in Park or Neutral, no vacuum should be indicated. With foot brake applied firmly, shift into Reverse. At low RPM, the gauge may or may not register a vacuum reading. If no reading is obtained, proceed as follows: Disconnect one wire from distributor modulator valve, shift in Neutral and increase engine speed to 1000-1500 RPM. Vacuum should be indicated. If no vacuum is indicated, disconnect both hoses at valve and connect hoses together with a nipple. Increase engine speed to 1000-1500 RPM, a vacuum reading indicates that vacuum supply is operational.