P1402
DTC P1402 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.
CONSULT-II Reference Value in Data Monitor Mode
On Board Diagnosis Logic
DTC Confirmation Procedure
NOTE:
- Diagnosis for this DTC will occur when engine coolant temperature is below 50 to 60 °C (122 to 140 °F). Therefore, it will be better to turn ignition switch ON (start engine) at the engine coolant temperature below 30 °C (86 °F) when starting DTC confirmation procedure.
- If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 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-II before starting DTC WORK SUPPORT test. If it is out of range below, the test cannot be conducted.
COOLAN TEMP/S : -10 to 50 °C (14 to 122 °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 engine coolant temperature or EGR temperature with a fan or means other than ambient air. Doing so may produce an inaccurate diagnostic result.
*: Although CONSULT-II screen displays "-10 to 40 °C (14 to 104 °F)" as a range of engine coolant temperature, ignore it.
WITH CONSULT-II
1. Turn ignition switch OFF, and wait at least 10 seconds, and then turn ON.
2. Select "EGR SYSTEM P1402" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT-II.
3. Touch "START".
4. Start engine and let it idle until "TESTING" on CONSULT-II 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 50 °C (14 to 122 °F). Retry from step 1.
5. 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 ON and select Service $01 with GST.
2. Check that engine coolant temperature is within the range of -10 to 50 °C (14 to 122 °F).
3. Check that voltage between ECM terminal 54 (EGR temperature sensor signal) and ground is less than 4.8 V.
4. Start engine and let it idle for at least 80 seconds.
5. Stop engine.
6. Turn ignition switch OFF, wait at least 10 seconds and then turn ON.
7. Select Service $07 with GST.
8. 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 - 6):
