Receiving ECM signal, linear solenoid type electronic EGR actuator operates Electric EGR control valve directly.
ECM performs EGR system feed back control with the information of measured mass air flow (The role of MAFS in diesel engine is different from gasoline engine. Fuel injection quantity is decided by MAFS signal in gasoline engine.)
When EGR gas(contains no oxygen) flowing into combustion chamber increases, the air passing through AFS(contains oxygen) decreases. Thus, with the output signal change of AFS accompanied by Electric EGR control valve actuation, ECM determine the amount of recirculated EGR gas quantity.
note
NOx is produced from the reaction of nitrogen and oxygen.
Controlling EGR gas(contains no oxygen) which is recirculated to combustion chamber, if least intake air required for complete combustion flows into combustion chamber, NOx decreases because there is no supplementary oxygen to react with nitrogen.
DTC Description
P401 is set when ECM detects that duty amount of EEGR actuator contol valve, ENG speed or amount of EGR is exceeded to minimum set point last to more than 15sec. In this case, check that stuck of EEGR actuator, air leakage of intake line.
DTC Detecting Condition
Item
Detecting Condition
Possible Cause
DTC Strategy
●
Signal monitoring
●
EGR actuator stuck
●
EGR actuator component
●
Air leakage of intake line
Enable Conditions
●
Engine running
Threshold Value
●
Real value - Target value > upper specified air amout value
Diagnostic Time
●
15 sec..
Fail Safe
Fuel cut
NO
EGR Off
YES
Fuel Limit
NO
MIL
YES
Specification
Electric EGR control valve
component resistance
Electric EGR control valve
operating Hz
Electric EGR control valve
operating duty
14.7 ~ 16.1Ω (20℃)
142Hz
5%(closed)~39%(opened)
Diagnostic Circuit Diagram
Signal Waveform
Fig.1) Approx. 5% duty signal waveform of Electric EGR control valve (with EEGR valve closed)
Fig.2) Approx. 57% duty signal waveform of Electric EGR control valve(with EEGR valve opened)
note
The output of approx. 5% duty is mainly for the diagnosis of Electric EGR control valve circuit than actuating EEGR.
Monitor GDS Data
1.
Connect GDS to Data Link Connector (DLC).
2.
Warm engine up to normal operating temperature.
3.
Turn "OFF" electrical devices and A/C.
4.
Monitor "AIR MASS PERCYLINDER" parameter on the GDS.
Specification : When Electric EGR control valve does not operate 5% duty) at idle : 340mg/st ± 50 mg/st
Fig1) Check if "AIR MASS PERCYLINDER"l is 340mg/st ± 50mg/st without EEGR operation at warm idle (Electric EGR control valve 6% duty)
warning
Electric EGR control valve operates as decelerating after rapid acceleration when idle EEGR does not operate, Electric EGR control valve operating duty decreases as time goes by. This controlling process lasts for about 1 min. and EElectric EGR control valve turns "OFF" (duty 5% ) after 1 min..
Terminal and Connector Inspection
1.
Electrical systems consist of a lot of harness and connectors, poor connection of terminals can cause various problems and damge of component.
2.
Perform checking procedure as follows.
(1)
Check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.
(2)
Check connecting condition of ECM and component connector : Check terminal seperation, damage of locking device and connecting condition between terminal and wiring.
note
Disconnect the pin which requires checking at male connector and insert it to the terminal at female connector for checking connecting condition. ( after checking, reconnect the pin at correct position. )
3.
Is the problem found?
▶ Repair the trouble causing part and go to "Verification of Vehicle Repair".
▶ Go to "Power Circuit Inspection".
Power Circuit Inspection
1.
Check power circuit voltage
(1)
IG KEY "OFF", ENGINE "OFF".
(2)
Disconnect Electric EGR control valve connector
(3)
IG KEY "ON".
(4)
Measure the voltage between power terminal of EGR actuator harness connector and chassis ground.
Secification : 11.5V~13.0V
(5)
Is the measured voltage within the specification?
▶ Go to "Control Circuit Inspection".
▶ Repair INJ FUSE in E/R FUSE & RELAY BOX and related circuit and go to "Verification of Vehicle Repair".
Control Circuit Inspection
1.
Check control circuit monitoring voltage
(1)
IG KEY "OFF", ENGINE "OFF".
(2)
Disconnect Electric EGR control valve connector.
(3)
IG KEY "ON".
(4)
Measure the voltage between control terminal of EGR actuator harness connector and chassis ground.
Specification : 3.2V~3.7V
(5)
Is the measured voltage within the specification?
▶ Go to "Component Inspection".
▶ When voltage is not detected : Go to "2. Check open in control circuit" as follows.
▶ When high voltage is detected : Repair short to battery and go to "Verification of Vehicle Repair".
2.
Check open in control circuit
(1)
IG KEY "OFF", ENGINE "OFF".
(2)
Disconnect Electric EGR control valve connector and ECM connector
(3)
Check continuity between control terminal of EGR actuator harness connector and ECM harness connector.
Specification : Continuity ( below 1.0Ω )
(4)
Is the measured resistance within the specification?
▶ Repair short to ground and go to "Verification of Vehicle Repair".
▶ Repair open in control circuit and go to "Verification of Vehicle Repair".
Component Inspection
1.
Check EGR actuator component resistance
(1)
IG KEY "OFF", ENGINE "OFF".
(2)
Disconnect EGR actuator.
(3)
Measure the resistance between power terminal and control terminal of EGR actuator (component side).
Secification : 7.3~ 8.8Ω (30°C)
(4)
Is EEGR actuator component resistance within the specification?
▶ Go to "2. Check EEGR actuator operation condition"as follows.
▶ Replace EEGR actuator and go to "Verification of Vehicle Repair".
2.
Check EEGR actuator operation condition
(1)
IG KEY "OFF", ENGINE "OFF"
(2)
Check that MAFS is installed in correctly according to the direction of arrow on MAFS assy’.
(3)
Check contamination of air cleaner filter.
(4)
IG KEY "ON", ENGINE "ON".
(5)
Let IDLE RPM last after warming engine up.
(6)
Check the leakage of intake system(the leakage or damage of intercooler).
(7)
Check that VGT operates correctly.( Check if vacuum operating state of VGT actuator is appropriate, if VGT diaphragm and unison ring are stuck.)
(8)
Check that EEGR actuator does not operate.
( EEGR actuator turns "OFF" and 6% duty is outputted 1 min. after rapid acceleration. )
(9)
Monitor signal voltage of MAFS when engine speed lasts at approx. 800RPM using GDS.
(10)
Check MAFS output signal at idle after rapid acceleration.(EEGR actuator duty 50%)
Specification : When EEGR actuator does not operate (6%) at idle : 340mg/st ± 50 mg/st
When EEGR actuator operates(50%) at idle : 200mg/st ± 50 mg/st
(11)
Is output signal within the specification?
▶ Go to "Verification of Vehicle Repair".
▶ Check that EEGR actuator is stuck. If it is, replace EEGR actuator assembly then, go to "Verification of Vehicle Repair".
Verification of Vehicle Repair
After a repair, it is essential to verify that the fault is corrected.
1.
After connecting GDS select "DIAGNOSTIC TROUBLE CODES(DTCs)" mode.
2.
Clear recorded DTC using GDS.
3.
Drive the vehicle within DTC "Enable conditions" in "General information".
4.
After selecting "DIAGNOSTIC TROUBLE CODES(DTCs)" mode and check if DTC is recorded again.
