DTC 0302
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 REFERENCE VALUE IN DATA MONITOR MODE
Specification data are reference values.
ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values, and are measured between each terminal and (25) (ECM ground).
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.
If EGR temperature sensor detects EGR flow under the condition that does not call for EGR, a low-flow malfunction is diagnosed.
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
CAUTION: Always drive vehicle at a sate speed.
NOTE:
- If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 10 seconds before conducting the next test.
- During the test, P0400 will not be stored in ECM even though "NG" is displayed on the CONSULT screen.
TESTING CONDITION:
- Before performing the following procedure, confirm battery voltage is more than 10 V at idle, then stop engine immediately
- It will be better to perform the test at a temperature above 5 °C (41 °F).
With Consult
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.
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 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. Select "EGR SYSTEM P0400" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT.
6. Touch "START".
7. Accelerate vehicle to a speed of 40 KPH (25 MPH) once and then stop vehicle.
If "COMPLETED" with "OK" appears on CONSULT screen, go to step 9.
If "COMPLETED" does not appear on CONSULT screen, go to the following step.
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 30 seconds or more.)
CKPS.RPM (POS): 1,800 - 2,800 rpm
Vehicle speed: Suitable speed
B/FUEL SCHDL: More than 3.5 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".
OR
With Generic Scan Tool
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: 1,800 - 2,800 rpm
Vehicle speed: Suitable speed
Voltage between ECM terminal (23) 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".
- When using GST, "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" should be performed twice as much as when using CONSULT or ECM (Diagnostic Test Mode II) because GST cannot display MODE 7 (1st trip DTC) concerning this diagnosis. Therefore, using CONSULT or ECM (Diagnostic Test Mode II) is recommended.
OR
Without Scan Tools
1. Turn ignition switch "OFF" and wait at least 10 seconds.
2. Turn ignition switch "ON".
3. Check voltage between ECM terminal (59) (engine coolant temperature sensor) and ground.
Voltage: More than 2.7 V
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 voltage between ECM terminal (59) (engine coolant temperature sensor) and ground. When the voltage becomes less than 1.8 V, immediately go to the next step.
5. Maintain the following conditions for at least 1 minute.
Engine speed: 1,800 - 2,800 rpm
Vehicle speed: Suitable speed
Voltage between ECM terminal (23) 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. Perform "Diagnostic Test Mode II" (Self-diagnostic results) with ECM.
9. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE".
WIRING DIAGRAM
DIAGNOSTIC PROCEDURE
COMPONENT INSPECTION
EGR temperature sensor
Check resistance change and resistance value.
If NG, replace EGR temperature sensor.
EGR volume control valve
With Consult
1. Disconnect EGR volume control valve harness connector.
2. Check resistance between the following terminals.
terminal (2) and terminals (1),(3)
terminal (5) and terminals (4),(6)
Resistance: 20.9 - 23.1 Ohm [At 20 °C (68 °F)]
3. Reconnect EGR volume control valve harness connector.
4. Remove air duct.
5. Remove EGR volume control valve from intake manifold collector.
(The EGR volume control valve harness connector should remain connected.)
6. Turn ignition switch "ON".
7. Perform "EGR VOL CONT/V" in "ACTIVE TEST" mode with CONSULT. Check that EGR volume control valve shaft moves smoothly forward and backward according to the valve opening.
If NG, replace the EGR volume control valve.
OR
1. Disconnect EGR volume control valve harness connector.
2. Check resistance between the following terminals.
terminal (2) and terminals (1),(3)
terminal (5) and terminals (4),(6)
Resistance: 20.9 - 23.1 Ohm [At 20 °C (68 °F)]
3. Turn ignition switch "ON" and "OFF". Check that EGR volume control valve shaft moves smoothly forward and backward according to the ignition switch position.
If NG, replace the EGR volume control valve.