Troubleshooting

Fig. 66 Vacuum & voltage chart.:

VACUUM IS AVAILABLE FOR CONDITION 1

1. Check for proper vacuum hose routing. If routing is satisfactory, replace EGR control valves A and B.

NO VACUUM AVAILABLE FOR CONDITION 2 & 3

1. Check for voltage at EGR control solenoid valve A. Voltage check should be made at yellow/white wire at box No. 1 yellow connector for Civic 1300 or blue wire on Civic 1500.
2. If voltage is not present, disconnect hose No. 15 from EGR control solenoid valve A. Check for vacuum at 4500 RPM. If vacuum is present, replace EGR solenoid valve A and repeat test. If vacuum is present, replace EGR solenoid valve A and repeat test. If vacuum is not present, check vacuum line routing and carburetor port.
3. If voltage is present in step 1 for Civic 1300, check thermosensor for proper operation. If satisfactory, replace control switch and repeat test.
4. If voltage is present in step 1 for Civic 1500, check for voltage at control unit blue wire connector with ignition switch On. If voltage is not present check blue wire between ignition coil and control unit.
5. Inspect vacuum switch A for proper operation, replace as required.
6. Check for voltage at control unit black/yellow wire connector with ignition switch On. If voltage is not present, check wiring for damage or defects.
7. Check continuity between control unit brown/black wire and suitable ground. Continuity should be present.

NO VOLTAGE IS AVAILABLE FOR CONDITION 2 BUT VACUUM IS GREATER THAN 2.75 IN. HG.

1. Replace EGR control solenoid valve B.

VOLTAGE IS AVAILABLE FOR CONDITION 1 OR 2, OR NO VOLTAGE FOR CONDITION 3 ON 1300 MODELS

1. Raise and support vehicle, then connect voltmeter or test lamp positive probe into yellow/black wire terminal at control box No. 1 connector. Connect negative probe to suitable ground.
2. Start engine, then place selector lever in second gear or No. 2 position. Accelerate slowly, while observing voltmeter.
3. Voltmeter should show battery voltage below 6 mph and no voltage above 12 mph. If voltmeter reading is not as specified, replace speed sensor and repeat test. If no voltage is present during test, proceed to step 4.
4. Check for bad electrical connection, fuse or defective speed sensor. Replace or repair as necessary and repeat steps 2 and 3.
5. Stop engine, lower vehicle and disconnect voltmeter.

NO VOLTAGE IS PRESENT FOR CONDITION 1 OR 3, OR VOLTAGE AVAILABLE FOR CONDITION 2 ON 1500 MODELS.

1. Check for voltage at control unit blue wire connector with ignition switch On. If voltage is not present, check blue wire between ignition coil and control unit.
2. Inspect vacuum switch A for proper operation, replace as required.
3. Check for voltage at control unit black/yellow wire connector with ignition switch On. If voltage is not present, check wiring for damage or defects.
4. Check for continuity between control unit brown/black wire and suitable ground. Continuity should be present.