1977 Manual Transmission Equipped Models
- With engine cold, start engine and check for vacuum at distributor retard vacuum unit. There should be no vacuum present. If vacuum is present, disconnect thermo sensor. If vacuum remains, replace ignition solenoid valve. If vacuum drops slightly, replace thermo sensor. See Fig 1.
- With engine idling at normal operating temperature, there should be vacuum to distributor vacuum retard unit. If no vacuum is present, check for vacuum at ignition solenoid valve. If no vacuum is present at solenoid valve, clean intake manifold vacuum port.
- If there is still no vacuum at solenoid valve, check voltage at solenoid valve. If voltage is present, replace solenoid valve. If no voltage is present, check for continuity across thermo sensor Yellow and Black/Yellow terminals. If no continuity exists, replace thermo sensor.
- If continuity exists, check for battery voltage at center terminal (Black/Yellow wire) of male connector. If no voltage is present, check wiring and fuses. Repair as necessary. If voltage is present, replace transmission sensor.
Courtesy of AMERICAN HONDA MOTOR CO., INC.