P0400

SYSTEM DESCRIPTION
This system cuts 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 is cut. This causes the vacuum to be discharged into the atmosphere. The EGR valve remains closed.
- Low engine coolant temperature
- Engine starting
- High-speed engine operation
- Engine idling
- Excessively high engine coolant temperature
- Mass air flow sensor malfunction
- Low intake air temperature

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. The vacuum signal passes through the solenoid valve. The signal then reaches the EGR valve. When the ECM sends an OFF signal, a plunger will then move to cut the vacuum signal from the intake manifold collector to the EGR valve.







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.

DTC Confirmation Procedure

CAUTION: Always drive vehicle at a safe speed.

NOTE:
- If "DTC Confirmation Procedure" has been previously conducted, always turn ignition switch OFF and wait at least 5 seconds before conducting the next test.
- P0400 will not be displayed at "SELF-DIAG RESULTS" mode with CONSULT-II even though DTC work support test result is "NG".

TESTING CONDITION: For best results, perform the test at a temperature above 5 °C (41 °F).

With CONSULT-II
1. Turn ignition switch ON.
2. Check "COOLAN TEMP/S" in "DATA MONITOR" mode with CONSULT-II and confirm it is within the range listed below.

COOLAN TEMP/S: Less than 40 °C (104 °F)

If the value is out of range, park the vehicle in a cool place and allow the engine temperature to stabilize. Do not attempt to lower the coolant temperature with a fan or means other than ambient air. Doing so may produce an inaccurate diagnostic result.

3. Start engine and let it idle monitoring "COOLAN TEMP/S" value. When the "COOLAN TEMP/S" value reaches 70 °C (158 °F), immediately go to the next step.
4. Select "EGR SYSTEM P0400" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT-II.
5. Touch "START".
6. Accelerate vehicle to a speed of 40 km/h (25 MPH) once and then stop vehicle with engine running.
If "COMPLETED" appears on CONSULT-II screen, go to step 9. If "COMPLETED" does not appear on CONSULT-II screen, go to the following step.
7. Check the output voltage of "THRTL POS SEN" (at closed throttle position) and note it.













8. When the following conditions are met, "TESTING" will be displayed on the CONSULT-II screen. Maintain the conditions until "TESTING" changes to "COMPLETED". (It will take approximately 30 seconds or more.
If "TESTING" is not displayed after 5 minutes, retry from step 2.
9. Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS". If "NG" is displayed, refer to "Diagnostic Procedure" below.

Overall Function Check
Use this procedure to check the overall EGR function. During this check, a 1st trip DTC might not be confirmed.













Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check the EGR valve lifting when revving engine from 2,000 rpm to 4,000 rpm quickly under no load using the following methods.
- Disconnect EGRC-solenoid valve harness connector. (The DTC for EGRC-solenoid valve will be displayed, however, ignore it.)
EGR valve should lift up and down without sticking.
If NG, go to "Diagnostic Procedure" below.

3. Check voltage between ECM terminal 63 (EGR temperature sensor signal) and ground at idle speed.

Less than 4.5 V should exist.
If NG, go to next step.

4. Turn ignition switch OFF.
5. Check harness continuity between EGR temperature sensor harness connector terminal 2 and ECM terminal 43 (ECM ground).
Continuity should exist.
6. Check "EGR TEMPERATURE SENSOR". Refer to "CHECK EGR TEMPERATURE SENSOR" in "Diagnostic Procedure" below.

Wiring Diagram

EC-EGRC1-01:

Main Harness And Room Harness Connector Views:

Diagnostic Procedure

Step 1:

Step 2:

Step 3 - 4:

Step 5 - 7:

Step 8 - 9:

Step 10:

Step 11 - 12: