Air Jet Control System Honda Civic III

DESCRIPTION & OPERATION

The primary main and slow air jet control system is used on Fed. 1500 HF models only. This system is designed to control air flow into carburetor main and slow air jets according to driving conditions and to maintain optimum air/fuel ratio.

When solenoid valves are activated by control unit, primary main and slow air jet cut-off solenoid valves supply additional air to each air passage of carburetor, leaning the air/fuel mixture.

CONTROL UNIT CONNECTOR

1. Check for voltage at control unit connector (Blue wire) with ignition on. There should be voltage. If no voltage, check Blue wire between control unit and ignition coil.
2. Check for voltage at control unit connector (Black/Yellow wire) with ignition on. There should be voltage. If no voltage, check fuse and wiring. Ensure Black wire between control unit and ground has continuity.

POWER VALVE CONTROL SOLENOID VALVE

1. Disconnect vacuum hose from power valve and connect vacuum pump. With ignition on, apply vacuum and listen for clicking sound from power valve. If no clicking sound is heard, replace carburetor. If clicking sound is heard, start engine.
2. Warm-up engine to normal operating temperature. Disconnect hose from power valve and connect vacuum gauge to hose. There should be no vacuum. If no vacuum, proceed to step 4).
3. If there is vacuum, check for voltage at Yellow/Black wire of No. 2 control box connector. If there is voltage, replace power valve control solenoid valve and retest. If there is no voltage, check fuse, wiring, and speed sensor, and retest.
4. Raise and support front of vehicle. Set parking brake and block rear wheels. Place vehicle in 2nd gear and check for vacuum at power valve hose No. 14 above 10 MPH. There should be vacuum. If there is vacuum, proceed to step 6).
5. If no vacuum, remove control box cover and check for voltage at power valve control solenoid valve. If there is voltage, replace vacuum switch B and retest. If there is no voltage, replace power valve control solenoid valve and retest.
6. With vehicle still in gear, and speed above 10 MPH, disconnect vacuum hose No. 1 from control box No. 2 at vacuum hose manifold. There should be no vacuum to power valve (hose No. 14). If there is no vacuum, system is okay. Reconnect vacuum hoses.
7. If there is vacuum, check for voltage at vacuum switch B with vehicle speed above 10 MPH. If there is no voltage, check fuse, wiring and speed sensor and retest. If there is voltage, remove control box cover. Check for continuity between terminals of vacuum switch B with vacuum hose No. 1 disconnected.
8. If there is continuity, replace power valve control solenoid valve and retest. If no continuity, replace vacuum switch B and retest.

CLUTCH SWITCH

1. Connect voltmeter or test light positive probe to Blue wire terminal of control unit connector. Connect negative probe to ground. Turn ignition on and depress clutch pedal. There should be voltage. If no voltage, check clutch switch.
2. Adjust or replace as necessary. If there is voltage, release clutch pedal and check for voltage. There should be no voltage. If no voltage, clutch switch is okay. If there is voltage, check clutch adjustment. Adjust as necessary and retest.

SPEED SENSOR

1. Raise and support front of vehicle. Set parking brake and block rear wheels. Connect voltmeter or test light positive probe to Yellow/Black wire terminal at control unit connector.
2. Connect negative probe to ground. Start engine. Place vehicle in 2nd position (gear selector in "2" position) and accelerate slowly. Battery voltage should be as shown in SPEED SENSOR VOLTAGE CHECK table. SPEED SENSOR VOLTAGE CHECK Speed Voltage Below 6 MPH Yes Above 12 MPH No
3. If voltmeter readings do not correspond to above MPH ranges, install a new speed sensor and retest. If there was no voltage during step 2), check for bad electrical connection, fuse or faulty speed sensor. Replace or repair as necessary and retest.

THERMOSENSOR B

Disconnect thermosensor leads and connect ohmmeter. Check for continuity between thermosensor terminals. There should be continuity when coolant temperature is below 113°F (45°C) and no continuity when above 113°F (45°C).

VACUUM SWITCH B

1. Raise and support front of vehicle. Set parking brake and block rear wheels. Disconnect No. 1 hose from control box No. 2 at vacuum hose manifold. Connect vacuum pump to hose. There should be voltage at Brown wire terminal of vacuum switch when vehicle speed is more than 10 MPH and more than 6 in. Hg vacuum is applied to switch.
2. Disconnect No. 1 hose from control box No. 2 at vacuum hose manifold. Connect vacuum pump to hose. There should be voltage at Brown/White wire terminal of vacuum switch when vehicle speed is more than 10 MPH and less than 6 in. Hg vacuum is applied to switch.

VACUUM SWITCH F

Disconnect No. 12 hose on control box No. 1 from vacuum hose manifold. Connect vacuum pump to hose. There should be voltage at Red wire terminal of vacuum switch when more than 12 in. Hg vacuum is applied to switch.

SYSTEM TESTING

1. Place vehicle on a chassis dynamometer or install a jumper wire from control box No. 2 (Green/White wire) to vehicle interior. Connect voltmeter positive probe to Green/White wire or jumper wire and negative probe to ground. Warm-up engine to normal operating temperature. Road test or run vehicle on dynamometer.
2. There should be voltage while the vehicle is cruising at a constant 30 MPH in 3rd gear. If there is voltage at 30 MPH in 3rd gear, proceed to step 5). If there is no voltage at 30 MPH in 3rd gear, and/or there is voltage on acceleration, voltage while in 1st or 2nd gear, or voltage above 3000 RPM, check the following
3. Check signal to power valve control solenoid valve. Check vacuum switch B, clutch switch, speed sensor, thermosensor B and vacuum switch F. Check for voltage at control unit connector (Blue wire) with ignition on. There should be voltage. If no voltage, check Blue wire between control unit and ignition coil.
4. Check for voltage at control unit connector (Black/Yellow wire) with ignition on. There should be voltage. If no voltage, check fuse and wiring. Ensure Black wire between control unit and ground has continuity.
5. Stop engine and remove jumper wire. Disconnect vacuum hoses No. 2 and No. 5 from control box No. 2 at vacuum hose manifold. Connect a vacuum pump to each hose. Apply vacuum. There should be vacuum. If there is vacuum at both hoses, proceed to step 7).
6. If there is no vacuum at hose No. 2, replace primary slow cut-off solenoid valve and retest. If there is no vacuum at hose No. 5, replace primary main air cut-off solenoid valve and retest.
7. Apply voltage to primary air cut-off solenoid valves. There should be no vacuum. If there is no vacuum at either hose, test is complete. If there is vacuum at hose No. 2, replace primary slow air cut-off solenoid valve and retest. If there is vacuum at hose No. 5, replace primary main air cut-off solenoid valve and retest.