By-Pass Control Solenoid Valves
- By-pass control solenoid valves are located at right front of engine compartment. Check by-pass valve shaft for binding, sticking, and smooth movement. If necessary, clean linkage and shafts with carburetor cleaner.
- Start and idle engine. Remove vacuum hose No. 2 from by-pass low control diaphragm. Connect vacuum gauge to hose. See Fig 1
. If vacuum is not present, go to step 6). If vacuum is present, go to next step.
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- Disconnect vacuum hose No. 8 from by-pass high control diaphragm. Connect vacuum gauge to hose. If vacuum is present, go to next step. If vacuum is not present, go to step 11.
- Increase engine speed to 3300 RPM. Check for vacuum at hose No. 2. If vacuum is not present, go to next step. If vacuum is present, go to step 16).
- Increase engine speed to 4000 RPM. Check for vacuum at hose No. 8. If vacuum is not present, system is okay. If vacuum is present, go to step 18).
- Remove vacuum hose No. 4 at by-pass low control solenoid. Connect vacuum gauge to hose. If vacuum is present, go to next step. If vacuum is not present, check vacuum line between solenoid and intake manifold. Repair as necessary and recheck.
- Turn ignition off. Unplug 6-wire connector from by-pass low control solenoid. See Fig 2
. Turn ignition on. Measure voltage between Black/Yellow (positive) and Red/Blue (negative) wire terminals. If battery voltage is present, replace by-pass low control solenoid valve. If voltage is not present, go to next step.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Measure voltage between Black/Yellow wire terminal and body ground. If battery voltage is not present, repair open in Black/Yellow wire between solenoid 6-wire connector and fuse No. 22. If battery voltage is present, go to next step.
- Turn ignition off. Install PGM-FI test harness connector between ECU and ECU harness connector. Check Red/Blue wire for continuity between ECU terminal A14 and solenoid connector.
- If continuity does not exist, repair open in Red/Blue wire. If continuity exists, substitute a known good ECU and retest. If symptom goes away, replace ECU.
- Remove vacuum hose No. 4 at by-pass high control solenoid. Connect vacuum gauge to hose. If vacuum is present, go to next step. If vacuum is not present, check vacuum line between solenoid and intake manifold. Repair as necessary and recheck.
- Turn ignition off. Unplug 6-wire connector from by-pass high control solenoid. Turn ignition on. Measure voltage between Black/Yellow (positive) and Red/Blue (negative) wire terminals. If battery voltage is present, replace by-pass high control solenoid valve. If voltage is not present, go to next step.
- Measure voltage between Black/Yellow wire terminal and body ground. If battery voltage is not present, repair open in Black/Yellow wire between solenoid 6-wire connector and fuse No. 22. If battery voltage is present, go to next step.
- Turn ignition off. Install PGM-FI test harness connector between ECU and ECU harness connector. Check Yellow wire for continuity between ECU terminal A18 and solenoid connector.
- If continuity does not exist, repair open in Yellow wire. If continuity exists, substitute a known good ECU and retest. If symptom goes away, replace ECU.
- Turn ignition off. Unplug 6-pin connector from by-pass low control solenoid. If vacuum is present, replace by-pass low control solenoid valve. If vacuum is not present, go to next step.
- Unplug connector "A" from ECU. Check Red/Blue wire for short to ground. Repair as necessary. If Red/Blue wire is okay, substitute a known good ECU and retest. If symptom goes away, replace ECU.
- Unplug 6-pin connector from by-pass high control solenoid valve. If vacuum is present, replace by-pass high control solenoid valve. If vacuum is not present, go to next step.
- Unplug connector "A" from ECU. Check yellow wire between connector and ECU terminal A18 for short to ground. Repair as necessary. If Yellow wire is okay, substitute a known good ECU and retest. If symptom goes away, replace ECU.