Electronic Speed Sensor Test
- Check the harness connection at the module. Start engine and run long enough to reach normal operating temperature.
- While watching the vacuum diaphragm assembly, accelerate slowly. The diaphragm should extend at speeds above 1850 RPM (±100), and retract at speeds below 1600 RPM. If not, perform the harness connector checks as follows. Number the harness terminals from 1 to 6 (or 8) from the key side of the connector.
- On models without electronic governor, turn key "ON" and connect one lead of voltmeter to terminal "1" and other lead to ground. Battery voltage should be indicated. Repeat test on terminals 4 and 6.
- Turn ignition off. Connect one lead on an ohmmeter to terminal "3" of connector and the other lead to terminal "1". Meter should read continuity. Repeat test, connecting terminal "5" to "1".
- On models with electronic governor, connect one lead of tachometer to terminal "1" and the other lead to terminal "2". Tachometer should read engine RPM.
- Connect one lead of voltmeter to terminal "1" and the other lead to terminal "8". With key "ON", voltmeter should read battery voltage.
- Connect one lead of ohmmeter to terminal "4" and the other lead to terminal "6". With key "OFF", ohmmeter should read continuity. Repeat test between terminals "5" and "7".
- If any of the terminals fail any of the tests, repair the wiring as required. If harness meets all specifications, replace the speed sensor module.
Courtesy of FORD MOTOR CO.