P0400
SYSTEM DESCRIPTION
This system controls flow rate of EGR led from exhaust manifold to intake manifold. The opening of the EGR by-pass passage in the EGR volume control valve changes to control the flow rate. A built-in step motor moves the valve in steps corresponding to the ECM output pulses. The opening of the valve varies for optimum engine control. The optimum value stored in the ECM is determined by considering various engine conditions. The EGR volume control valve remains close under the following conditions.
- Engine stopped
- Engine starting
- Engine idling
- Low engine coolant temperature
- Excessively high engine coolant temperature
- High engine speed
- Wide open throttle
- Low battery voltage
COMPONENT DESCRIPTION
EGR volume control valve
The EGR volume control valve uses a step motor to control the flow rate of EGR from exhaust manifold. This motor has four winding phases. It operates according to the output pulse signal of the ECM. Two windings are turned ON and OFF in sequence. Each time an ON pulse is issued, the valve opens or closes, changing the flow rate. When no change in the flow rate is needed, the ECM does not issue the pulse signal. A certain voltage signal is issued so that the valve remains at that particular opening.
CONSULT-II Reference Value in Data Monitor Mode
Specification data are reference values.
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.
Malfunction is detected when no EGR flow is detected under condition that calls for EGR.
Possible Cause
- Harness or connectors
(EGR volume control valve circuit is open or shorted. )
- EGR volume control valve stuck closed
- Dead (Weak) battery
- EGR passage clogged
- EGR temperature sensor and circuit
- Exhaust gas leaks
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 10 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:
- Before performing the following procedure, confirm battery voltage is more than 10 V at idle, then stop engine immediately.
- For best results, perform the test at a temperature of 5° C (41° F) or higher.
WITH CONSULT-II
1. Turn ignition switch "OFF" and wait at least 10 seconds.
2. Turn ignition switch "ON"
3. Check "COOLAN TEMP/S" in "DATA MONITOR" mode with CONSULT-II.
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.
4. Start engine and let it idle monitoring "COOLAN TEMP/S" value. When the "COOLAN TEMP/S" value reaches 60° C (140° F), immediately go to the next step.
5. Select "EGR SYSTEM P0400" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT-II.
6. Touch "START".
7. Accelerate vehicle to a speed of 40 KPH (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.
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.)
CKPS.RPM (POS) 1,200.2,400 rpm
Vehicle speed Suitable speed
B/FUEL SCHDL More than 4 msec
THRTL POS SEN 0.65 - 1.08 V
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.
WITH GST
1. Turn ignition switch "OFF" and wait at least 10 seconds.
2. Turn ignition switch "ON".
3. Check engine coolant temperature in MODE 1 with GST.
Engine coolant temperature: 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.
4. Start engine and let it idle monitoring the value of "COOLAN TEMP/S". When the engine coolant temperature reaches 60° C (140° F), immediately go to the next step.
5. Maintain the following conditions for at least 1 minute.
Engine speed: 1,200 - 2,400 rpm
Vehicle speed: Suitable speed
Voltage between ECM terminal 91 and ground: 0.65 - 1.08 V
Selector lever: Suitable position
6. Stop vehicle.
7. Turn ignition switch "OFF" and wait at least 10 seconds, then turn "ON".
8. Repeat step 3 to 5.
9. Select "MODE 3" with GST.
10. If DTC is detected, go to "Diagnostic Procedure" below.
- When using GST, "DTC Confirmation Procedure" should be performed twice as much as when using CONSULT-II because GST cannot display MODE 7 (1st trip DTC) concerning this diagnosis. Therefore, using CONSULT-II is recommended.
EC-EGRC1-01:
EC-EGRC1-01 - Connector View:
Wiring Diagram
ECM TERMINALS AND REFERENCE VALUE MEASURED BETWEEN EACH TERMINAL AND 48.:
Diagnostic Procedure
Diagnostic Procedure Step 1:
Diagnostic Procedure Step 2:
Diagnostic Procedure Step 3:
Diagnostic Procedure Step 4:
Diagnostic Procedure Step 5:
Diagnostic Procedure Step 6:
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Diagnostic Procedure Step 9:
Diagnostic Procedure Step 10:
