Frequency Solenoid C (Auto. Trans. Only)

1. Disconnect frequency solenoid C connector. Disconnect lower hose from frequency solenoid valve C and connect vacuum pump. Disconnect upper hose from frequency solenoid valve C. See Fig 1 .
2. Apply vacuum to solenoid valve C. If solenoid does not hold vacuum, replace solenoid. If vacuum holds, connect a vacuum gauge to upper frequency valve C hose. Jumper battery voltage to Blue/Red wire solenoid terminal. Jumper Black wire terminal to ground. Apply vacuum.
3. If vacuum is indicated on gauge connected to upper hose fitting, go to step 4). If vacuum is not indicated on gauge, replace frequency solenoid valve C.
4. Disconnect jumper wires from solenoid terminals. If vacuum is now indicated on gauge, replace frequency solenoid valve C. If vacuum is not indicated on gauge, reconnect vacuum hoses and electrical connector to solenoid. Start engine and warm to operating temperature (cooling fan comes on).
5. Measure voltage between ECU terminal No. 21 Blue/Red (pos.) wire and ECU terminal No. 32 Black (neg.) wire terminals. If voltage is 5-6 volts, fault is in ECU control circuit. Go to TROUBLE SHOOTING  . If voltage is not 5-6 volts, repair open or short in Blue/Red or Black wires between solenoid and ECU.

Fig 1: Testing Frequency Solenoid Valve C

Courtesy of AMERICAN HONDA MOTOR CO., INC.