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P0400


DTC P0400 EGR FUNCTION





Description

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.

[Reference data]











CAUTION:
Never 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-III 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.









DTC Confirmation Procedure

CAUTION:
Always drive vehicle at a safe speed.

NOTE:
- If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next step.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
- P0400 will not be displayed at "SELF-DIAG RESULTS" mode with CONSULT-III 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-III
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-III.
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-III.
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-III screen, go to step 8.
If "COMPLETED" does not appear on CONSULT-III screen, go to the following step.
7. When the following conditions are met, "TESTING" will be displayed on the CONSULT-III 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 "Diagnosis Procedure".

WITH GST
1. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
2. Check engine coolant temperature in Service $01 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 following conditions for at least 1 minute.
Engine speed: 1,200 - 2,800 rpm
Vehicle speed: More than 10 km/h (6 MPH)
Shift lever: Suitable position
5. Stop vehicle.
6. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
7. Select Service $07 with GST.
8. Check 1st trip DTC.
9. If 1st trip DTC is detected, go to "Diagnosis Procedure".




Wiring Diagram

EC-EGRC1-01:





Specification data are reference values and are measured between each terminal and ground.

CAUTION:
Never use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.









Diagnosis Procedure
1.CHECK EXHAUST SYSTEM
1. Start engine.
2. Check exhaust pipes and muffler for leaks.






OK or NG
OK - GO TO 2.
NG - Repair or replace exhaust system.
2.CHECK EGR VOLUME CONTROL VALVE POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.






2. Disconnect EGR volume control valve harness connector.
3. Turn ignition switch ON.






4. Check voltage between EGR volume control valve terminals 2, 5 and ground with CONSULT-III or tester.

Voltage: Battery voltage

OK or NG
OK - GO TO 4.
NG - GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E5, F14
- Harness for open or short between EGR volume control valve and IPDM E/R
- Repair harness or connectors.
4.CHECK EGR VOLUME CONTROL VALVE OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminals and EGR volume control valve terminals as follows. Refer to Wiring Diagram.






Continuity should exist.


4. Also check harness for short to ground and short to power.
OK or NG
OK - GO TO 5.
NG - Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK EGR PASSAGE
Check EGR passage for clogging and cracks.
OK or NG
OK - GO TO 6.
NG - Repair or replace EGR passage.
6.CHECK EGR VOLUME CONTROL VALVE
Refer to P0403.
OK or NG
OK - GO TO 7.
NG - Replace EGR volume control valve.
7.CHECK EGR TEMPERATURE SENSOR AND CIRCUIT
Perform DTC Confirmation Procedure for DTC P0405, P0406. Refer to P0405.
OK or NG
OK - GO TO 8.
NG - Repair or replace malfunctioning part.
8.CHECK INTERMITTENT INCIDENT
Refer to Description Diagnosis Procedure.
- INSPECTION END
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