Accord & Prelude
- Check by-pass valve shaft for binding, sticking and smooth movement. Ensure by-pass valve is in close contact with stopper when by-pass valve is fully open. Ensure by-pass valve is in close contact with full close screw when by-pass valve is fully closed. See Fig 1
.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- Clean linkage and shafts with carburetor cleaner if fault is found. Start engine and allow to idle. Remove vacuum hose from by-pass control diaphragm and attach a vacuum gauge to hose. See Fig 2
. Check for vacuum. If vacuum is present, go to step 4).
- If no vacuum is present, disconnect vacuum supply hose from by-pass control solenoid. Check for vacuum. If vacuum is present, proceed to step 6). If no vacuum is present, check vacuum line between solenoid and intake manifold. Repair as necessary.
- If vacuum was present in step 2), increase engine speed to 5000 RPM and check vacuum gauge. If vacuum is not present, by-pass control system is functioning properly. If vacuum is present, disconnect 4 or 6-wire solenoid connector. See Fig 3
. If vacuum is now present, replace by-pass control solenoid valve.
- If no vacuum is present with solenoid connector unplugged, turn ignition off. Connect System Checker Harness (07999-PD6000A) between ECU and ECU connector. Disconnect "A" connector from ECU only, not main harness. Check for continuity to ground on Yellow wire between ECU terminal A8 and 4 or 6-wire connector. If continuity exists, repair short to ground in Yellow wire. If continuity does not exist, substitute a known good ECU and retest. If symptom is rectified, replace original ECU.
- If vacuum was present at solenoid in step 3), disconnect 4 or 6-wire solenoid connector. See Fig 3
. Measure voltage between Black/Yellow (pos.) and Yellow (neg.) terminals. If battery voltage is present, replace by-pass control solenoid.
- If no battery voltage was present in step 6), measure voltage between Black/Yellow terminal and body ground. If no battery voltage is present, repair open in Black/Yellow wire between connector and No. 11 (Accord) or No. 12 (Prelude) fuse or replace fuse.
- If battery voltage was present in step 7), turn ignition off. Attach System Checker Harness (07999-PD6000A) between ECU and solenoid connector. Check for continuity of Yellow wire between 4 or 6-wire connector and ECU terminal A8.
- If continuity does not exist, repair open in Yellow wire. If continuity is present, substitute a known good ECU and retest. If symptom is rectified, replace original ECU.
Courtesy of AMERICAN HONDA MOTOR CO., INC.