P1402
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 EGR temperature sensor detects EGR flow under the condition that does not call for EGR, a high-flow malfunction is diagnosed.
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
TESTING CONDITION:
- Always perform the test at a temperature above -10 °C (14 °F).
- Engine coolant temperature and EGR temperature must be verified in "DATA MONITOR" mode with CONSULT before starting DTC WORK SUPPORT test. If it is out of range below, the test cannot be conducted.
COOLAN TEMP/S: -10 to 35 °C (14 to 95 °F)*
EGR TEMP SEN: Less than 4.8 V
If the values are out of the ranges indicated above, park the vehicle in a cool place and allow the engine temperature to stabilize. Do not attempt to reduce the coolant or EGR temperature with a fan or means other than ambient air. Doing so may produce an inaccurate diagnostic result.
*: Although CONSULT screen displays "-10 to 40 °C (14 to 104 °F)" as a range of coolant temperature condition, ignore it.
With Consult
1. Turn ignition switch "ON".
2. Select "EGR SYSTEM P1402" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT.
3. Touch "START".
4. Start engine and let it idle until "TESTING" on CONSULT screen is turned to "COMPLETED". (It will take 80 seconds or more.)
If "TESTING" is not displayed after 5 minutes, turn ignition "OFF" and cool the engine coolant temperature to the range of -10 to 35 °C (14 to 95 °F). Retry from step 1.
5. Make sure that "OK" is displayed after touching "SELFDIAG RESULTS". If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".
OR
With Generic Scan Tools
1. Turn ignition switch "ON" and select "MODE 1" with GST.
2. Check that engine coolant temperature is within the range of -10 to 35 °C (14 to 95 °F).
3. Check that voltage between ECM terminal (63)(EGR temperature) and ground is less than 4.8 V.
4. Start engine and let it idle for at least 80 seconds.
5. Stop engine.
6. Perform from step 1 to 4.
7. Select "MODE 3" with GST.
8. 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 "NO".
2. Check the following voltages.
ECM terminal (59) (engine coolant temperature) and ground: 1.5 - 4.4 V
ECM terminal (63) (EGR temperature) and ground: Less than 4.8 V
3. Start engine and let it idle for at least 80 seconds.
4. Turn ignition switch "OFF", wait at least 10 seconds and then turn "ON".
5. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
6. 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 ohms [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
Without 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 ohms [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.