Testing

1. Disconnect solenoid valve harness connector and connect voltmeter.
2. Check that battery voltage does not exist when engine is idling and then raced.
3. When engine coolant temperature is between 86-212'F, check that battery voltage exists when engine is idling then race engine and check that battery voltage disappears.
4. If above test results are not as described, check revolution sensor, potentiometer, and electrical circuits and, if they appear normal, replace EGR control unit