ECC System (California)

Fig. 25 ECC & exhaust gas sensor electrical connectors:

1. Disconnect ECC inspection electrical connector and connect exhaust gas sensor inspection electrical connector, Fig. 25.
2. Turn ignition switch on and observe ECC inspection lamp on instrument panel. If lamp lights, proceed to step 3. If lamp does not light, replace lamp bulb.
3. Start engine and run until normal operating temperature is reached.
4. Run engine at 2000 RPM for approximately five minutes, the observe inspection lamp on instrument panel. If lamp lights, the system is functioning normally. If lamp does not light, proceed to step 5.
5. Turn engine off, then connect ECC inspection electrical connector.
6. Run engine and note inspection lamp. If lamp does not light, locate and repair open in exhaust sensor circuit. If lamp cycles on and off, remaining on longer than off, proceed to step 7. If lamp cycles on and off, remaining off longer than on, proceed to step 8.
7. Check individual solenoids as follows:
a. With ignition switch off, ensure all harness connectors are secure, correcting as needed.
b. Disconnect electrical connectors from air/fuel ratio solenoid and anti-dieseling solenoid.
c. Measure resistance of each solenoid. Air/fuel solenoid resistance should measure 30-50 ohms and anti-dieseling solenoid resistance should measure 25-45 ohms. If air/fuel ratio solenoid resistance is not within specifications, replace the valve. If anti-dieseling solenoid resistance is not within specifications replace the valve and recheck system.
d. Reconnect solenoid electrical connectors, then disconnect 10-pin connector from ECC unit.

Fig. 26 Solenoid test connections & specifications:

e. Turn ignition switch on, then disconnect alternator terminal L and measure voltage between each terminal and ground, Fig. 26. If voltage(s) is not within specifications, repair or replace harness as necessary. If voltages are within specifications, replace ECC control unit and recheck system.

Fig. 27 Water temperature sensor resistance specifications:

8. Check individual sensors as follows:
a. With ignition switch off, ensure all harness connectors are secure, correcting as needed.
b. Disconnect 20-pin connector from ECC control unit.
c. Disconnect exhaust gas sensor electrical connector, then connect jumper wire between ground and connector terminal.
d. Check for continuity between 20-pin connector terminal 2 and ground. If continuity exists, replace exhaust gas sensor. If there is no continuity, repair of replace ECC harness as necessary. If inspection lamp continues to cycle as indicated in step 6, proceed to step e.
e. Measure water temperature sensor resistance between 20-pin connector terminals 8 and 16. At temperatures below 68°F, resistance should measure less than 2.9k ohms. At temperatures of 68°F or above, resistance should measure 2.1k ohms or more. If resistance is within specifications, replace ECC control unit and recheck system. If resistance is not within specifications, proceed to step f.
f. Position water temperature sensor in a container of water and measure resistance when heated to various temperatures, Fig. 27. If resistance readings are within specifications, repair or replace ECC harness as necessary. If readings are not within specifications, replace water temperature sensor, then recheck system.