Automatic Transmission

With engine at normal operating temperature and ambient temperature above 70°F, check the following:

1. Using a "T" fitting, place a vacuum gauge between distributor and solenoid vacuum valve. Raise rear wheels. Disconnect and plug vacuum line at vacuum switch on control unit assembly. Start engine and run at fast idle (above 850 RPM). Vacuum gauge should read zero. Remove electrical lead from control unit "T" connector, vacuum gauge should indicate vacuum. Reconnect wire and gauge should drop to zero.
2. Unplug and reconnect vacuum line to vacuum switch, and disconnect single wire lead from control unit to speed switch. Gauge should indicate vacuum. A sharp acceleration will cause vacuum gauge to drop to zero sharply. Limit speed to 40 MPH. As engine RPM stabilizes, vacuum should be restored and gauge should indicate vacuum advance. Reconnect speed switch lead.
3. Disconnect and plug vacuum line at vacuum switch. Vacuum gauge should be zero. Accelerate engine to above 30 MPH, vacuum gauge should indicate normal vacuum advance when about 30 MPH is reached.

   If no solenoid action occurred in foregoing procedures, replace control unit assembly. Repeat tests to be sure problem was corrected. Reconnect vacuum lines as before test and be sure all wires are securely connected.