Speed Continuously Changes Up and Down

1. Check actuator cable for proper operation. If satisfactory, proceed to step 2. If not satisfactory, service or adjust cable as required.
2. Perform servo test. If servo is satisfactory, proceed to step 3. If not satisfactory, replace servo as required.
3. Ensure proper speedometer cable routing and cable is not bent or binding. If satisfactory, proceed to step 4. If not satisfactory, service cable is required.
4. Inspect speed sensor for free operation or faulty speedo gear, coil resistance is about 200 ohms, at 30 mph, output voltage is constantly in the range of 2.4-4.9 volts RMS with a 4000 ohms resistance load. If satisfactory, proceed to step 5. If not satisfactory, replace speed sensor or speedo gear.
5. Perform speed sensor test. If satisfactory, proceed to step 6. If not satisfactory, replace speed sensor.
6. Check vacuum dump valve. If satisfactory, proceed to step 7. If not satisfactory, service or adjust vacuum dump valve as required.
7. Perform amplifier test. If test corrects problem, replace amplifier. If test does not correct problem, check circuit connections for good contacts and check servo feedback wiring for correct color code location and shorted or open wiring, then service as required.