DTC 0302

SYSTEM DESCRIPTION
This system outs and controls vacuum applied to the EGR valve to suit engine operating conditions. This cut-and-control operation is accomplished through the ECM and the EGRC-solenoid valve. When the ECM detects any of the following conditions, current flows through the solenoid valve. This causes the port vacuum to be discharged into the atmosphere. The EGR valve remains closed.
- Low engine coolant temperature
- Engine starting
- Engine stopped
- Engine idling
- Excessively high engine coolant temperature
- Mass air flow sensor malfunction


COMPONENT DESCRIPTION





Exhaust gas recirculation (EGR) valve
The EGR valve controls the amount of exhaust gas routed to the intake manifold. Vacuum is applied to the EGR valve in response to throttle valve opening. The vacuum controls the movement of a taper valve connected to the vacuum diaphragm in the EGR valve.






EGRC-solenoid valve
The EGRC-solenoid valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the coil in the solenoid valve is energized. A plunger will then move to flow the vacuum signal [from the intake manifold collector to the EGR valve.]

The vacuum signal passes through the solenoid valve. The signal then reaches the EGR valve. When the ECM sends an OFF signal, the plunger is returned by the spring which cuts the vacuum signal.






CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Specification data are reference values.






ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values, and are measured between each terminal and (25) (ECCS ground).









ON BOARD DIAGNOSIS LOGIC
If the absence of EGR flow is detected by EGR temperature sensor under the condition that calls for EGR, a low-flow malfunction is diagnosed.

It EGR temperature sensor detects EGR flow under the condition that does not call for EGR, a high-flow malfunction is diagnosed.



DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

CAUTION: Always drive vehicle at a sate speed.

NOTE:
- If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
- During the test, P0400 will not be stored in ECM even though "NG" is displayed on the CONSULT screen.

TESTING CONDITION:
Always perform the test at a temperature of -10°C (14°F) or higher.


OVERALL FUNCTION CHECK
Use this procedure to check the overall EGR function. During this check, a 1st trip DTC might not be confirmed.






Without TOOLS
(1) Start engine and warm it up to normal operating temperature.






(2) Check the EGR valve lifting when revving engine up to 3,000 rpm quickly under no load.
EGR valve should lift up and down without sticking.









(3) Check voltage between EGR temperature sensor harness connector terminal (1) and ground at idle speed. Less than 4.5V should exist.
(4) Turn ignition switch "OFF".
(5) Check harness continuity between EGR temperature sensor harness connector terminal (2) and ECM terminal (43).
Continuity should exist.

(6) Perform "COMPONENT INSPECTION", "EGR temperature sensor".







Electrical Diagrams






Circuit Connectors

1 Of 2:

DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION






EGR valve
Apply vacuum to EGR valve vacuum port with a hand vacuum pump.
EGR valve spring should lift.
Check for sticking.
If NG, repair or replace EGR valve.









EGRC-solenoid valve
Check solenoid valve, following the table as shown below:
If NG, replace the solenoid valve.












EGR temperature sensor
Check resistance change and resistance value.
If NG, replace EGR temperature sensor.






EGRC-BPT valve
1. Plug one of two ports of EGRC-BPT valve.
2. Vacuum from the other port and check for leakage while applying a pressure above 0.981 kPa (100 mmH2O, 3.94 inH2O) from under EGRC-BPT valve.
3. If a leakage is noted, replace the valve.