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 does not flow through the solenoid valve. This causes the intake manifold 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
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 and EGRC-BPT valve operation. 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 (from the intake manifold collector to the EGR valve. 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.
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 even though DTC work support test result is NG.
TESTING CONDITION:
For best results, perform the test at a temperature of 5°C (41°F) or higher.
With CONSULT
1. Turn ignition switch "ON"
2. Check "COOLAN TEMP/S" in "DATA MONITOR" mode with CONSULT.
Confirm COOLAN TEMP/S value 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 engine 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
5. Touch "START".
6. Accelerate vehicle to a speed of 40 kph (25 MPH) once and then stop vehicle with engine running.
If "COMPLETED" appears on CONSULT screen, go to step 9. If "COMPLETED" does not appear on CONSULT screen, go to the following step.
7. Check the output voltage of "THRTL POS SEN" (at closed throttle position) and node it.
8. When the following conditions are met, "TESTING" will be displayed on the CONSULT screen. Maintain the conditions until "TESTING" changes to "COMPLETED". (It will take approximately 60 seconds or more.)
CMPS.RPM (POS) 1,600 - 2,400 rpm (A/T)
1,800 - 2,600 rpm (M/T)
B/FUEL SCHDL 3.0 - 4.5 msec
THRTL POS SEN X - (x + 0.7) V
X = Voltage value measured at step 7
Selector lever Suitable position
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
1. Start engine and warm it up to normal operating temperature.
2. Check the EGR valve lifting when revving engine from idle up to 3,000 rpm quickly under no load.
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 4.5V should exist.
If NG, go to next step.
4. Turn ignition switch "OFF".
5. Disconnect EGR temperature sensor harness connector.
6. Check harness continuity between EGR temperature sensor harness connector terminal 2 and ground.
Continuity should exist.
7. Perform "EGR TEMPERATURE SENSOR", "Component Inspection".
Wiring Diagram
EC-EGRC1-01:
EC-EGRC1-01 Connectors View:
Diagnostic Procedure
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Step 7:
Step 8:
Step 9:
Step 10:
Step 11:
Component Inspection
EGR VALVE
Apply vacuum to EGR vacuum port with a hand vacuum pump.
EGR valve spring should lift.
- Check for sticking.
If NG, repair or replace EGR valve.
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.