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1975-76 Manual Transmission Equipped Models

  1. Disconnect vacuum hose at distributor diaphragm and connect vacuum gauge to it. With transmission in Neutral and engine at 2000 RPM, vacuum gauge should read zero (0).
  2. If vacuum is present, check voltage at solenoid with ignition on. If voltage is present, replace solenoid valve. If voltage is not present, check transmission sensor and Yellow wire.
  3. With transmission in 4th gear and engine at 2000 RPM, vacuum gauge should read 3 in. Hg and increase as throttle is opened. If no vacuum is present, check transmission sensor. Sensor should be open in 4th gear, closed in all other gear positions.
  4. If vacuum is below 3 in. Hg, disconnect vacuum hose from solenoid valve and install vacuum gauge in line. If vacuum is still low, plug vacuum line to charcoal canister from idle cut-off valve. If vacuum remains low, check engine mechanical condition.
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