P0400
DTC P0400 EGR FUNCTIONDescription
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 closed 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.
EGR Temperature Sensor
The EGR temperature sensor detects temperature changes in the EGR passageway. When the EGR volume control valve opens, hot exhaust gases flow, and the temperature in the passageway changes. The EGR temperature sensor is a thermistor that modifies a voltage signal sent from the ECM. This modified signal then returns to the ECM as an input signal. As the temperature increases, EGR temperature sensor resistance decreases.
This sensor is not directly used to control the engine system. It is used only for the on board diagnosis.
CAUTION: Do not use ECM ground terminals when measuring input/output voltage. Doing so may damage the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
When EGR system is operating.
Voltage: 0 - 1.5 V
CONSULT-II Reference Value in Data Monitor Mode
On Board Diagnosis Logic
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:
- 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, wait at least 10 seconds and then turn ON.
2. Check "COOLAN TEMP/S" in "DATA MONITOR" mode with CONSULT-II.
Confirm "COOLAN TEMP/S" value is within the range listed.
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-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 8.
If "COMPLETED" does not appear on CONSULT-II screen, go to the following step.
7. When the given 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.
8. 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, wait at least 10 seconds and then turn ON.
2. 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.
3. Start engine and let it idle monitoring the engine coolant temperature value. When the engine coolant temperature reaches 70 °C (158 °F), immediately go to the next step.
4. Maintain the given conditions for at least 1 minute.
Engine speed: 1,200 - 3,600 rpm
Vehicle speed: More than 10 km/h (6 MPH)
Selector lever: Suitable position
5. Select Service $07 with GST.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.
EC-EGRC1-01:
Wiring Diagram
Diagnostic Procedure
Diagnostic Procedure (Step 1):
Diagnostic Procedure (Steps 2 - 4):
